AQA Triple Science: Physics — Recall & Retrieval

4.1.1.1 Energy stores and systems

1.

What is meant by a system in physics?

A system is an object or group of objects being studied where energy can be transferred.

2.

What happens to the energy stores of a system when a change occurs?

Energy is transferred between different energy stores when a change occurs.

3.

Describe the energy store changes when an object is projected upwards.

The kinetic energy store decreases and the gravitational potential energy store increases.

4.

Describe the energy store changes when a moving object hits an obstacle.

The kinetic energy store decreases and energy is transferred to thermal, sound and elastic potential energy stores.

5.

Describe the energy store changes when water is heated in an electric kettle.

Electrical energy is transferred to the thermal energy store of the water.

6.

How can energy changes in a system be calculated?

Energy changes can be calculated using equations that link energy transfers to quantities such as mass, velocity, height, power and temperature change.

4.1.1.2 Changes in energy

1.

A football has a mass of 0.45 kg and is kicked at a speed of 30 m/s. Calculate the kinetic energy of the football.

202.5 J

2.

A car has a mass of 1200 kg and travels at 20 m/s. Calculate the kinetic energy of the car.

240,000 J

3.

A spring with a spring constant of 200 N/m is stretched by 0.05 m. Calculate the elastic potential energy stored in the spring.

0.25 J

4.

A spring is stretched by 0.06 m and stores 0.54 J of elastic potential energy. Calculate the spring constant.

300 N/m

5.

An object is raised 5 m and gains 750 J of gravitational potential energy. If the gravitational field strength is 10 N/kg, calculate the mass of the object.

15 kg

6.

A 5 kg object is lifted 3 m. If the gravitational field strength is 9.8 N/kg, calculate the gravitational potential energy gained.

147 J

4.1.1.3 Energy changes in systems

1.

A substance requires 6000 J of energy to increase its temperature by 10°C. If the substance has a mass of 2 kg, calculate its specific heat capacity.

300 J/kg°C

2.

What is meant by the specific heat capacity of a substance?

The energy needed to raise the temperature of 1 kg of a substance by 1°C.

3.

Calculate the energy needed to raise the temperature of 1 kg of a substance with a specific heat capacity of 500 J/kg°C by 10°C.

5000 J

4.

What factors affect the amount of thermal energy stored by an object when its temperature changes?

Mass, temperature change and specific heat capacity.

5.

Describe how the specific heat capacity of a material can be investigated experimentally.

Measure the mass of the material, heat it with a known energy input, measure the temperature change and calculate the specific heat capacity.

6.

During heating, which energy store decreases and which energy store increases?

The energy store of the heater decreases and the thermal energy store of the object increases.

4.1.1.4 Power

1.

What is meant by power in physics?

Power is the rate of energy transfer.

2.

A device transfers 9000 J of energy and has a power of 300 W. Calculate the time taken for the energy transfer.

30 seconds

3.

What equation is used to calculate power from work done and time?

Power = Work done ÷ Time

4.

A machine transfers 6000 J of energy in 30 seconds. Calculate its power.

200 W

5.

What is the unit of power?

Watts (W)

6.

Why is a machine that transfers the same amount of energy in less time more powerful?

It transfers the same amount of energy in a shorter time, so the energy transfer rate is higher.

4.1.2.1 Energy transfers in a system

1.

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transferred between stores.

2.

What happens to the total energy in a closed system when an energy transfer occurs?

The total energy remains constant in a closed system.

3.

What is meant by dissipated energy?

Dissipated energy is energy transferred to unwanted stores, usually thermal energy in the surroundings.

4.

Why is dissipated energy often described as wasted energy?

It is described as wasted because it is transferred to stores that are not useful.

5.

How can lubrication reduce unwanted energy transfers?

Lubrication reduces friction, lowering unwanted thermal energy transfers.

6.

How does increasing the thickness of insulation affect the rate of cooling of a building?

Increasing insulation thickness reduces the rate of cooling because less thermal energy is transferred to the surroundings.

4.1.2.2 Efficiency

1.

A device has an efficiency of 75% and takes in 2000 J of energy. Calculate the useful energy output.

1500 J

2.

What does an efficiency value of 0.8 mean?

0.8 means 80% of the input energy is transferred usefully.

3.

A machine has a useful power output of 1500 W and an efficiency of 60%. Calculate the total power input.

2500 W

4.

How can efficiency be converted from a decimal into a percentage?

Multiply the decimal by 100.

5.

A machine takes in 500 J of energy and transfers 400 J usefully. Calculate the efficiency of the machine.

80%

6.

How can the efficiency of an energy transfer be increased?

Reduce unwanted energy transfers, such as friction and heat loss.

4.1.3 National and global energy resources

1.

What are the main non-renewable energy resources used on Earth?

Coal, oil, natural gas and nuclear fuels.

2.

What are the main renewable energy resources used on Earth?

Wind, solar, hydroelectric, tidal, wave, geothermal and biofuels.

3.

What is the difference between renewable and non-renewable energy resources?

Renewable resources are replaced naturally; non-renewable resources are finite and will eventually run out.

4.

Describe one advantage and one disadvantage of using fossil fuels.

Advantage: reliable and high energy output. Disadvantage: fossil fuels release carbon dioxide and contribute to climate change.

5.

Why are some energy resources more reliable than others?

Some resources depend on weather conditions, while others can produce energy continuously.

6.

Why can the use of different energy resources cause environmental issues?

Different resources can cause pollution, greenhouse gas emissions, waste or damage to habitats.

Topic 1 Review

1.

Explain how energy stores change when an object is lifted and then released.

When an object is lifted, energy is transferred to the gravitational potential energy store. When released, this transfers to the kinetic energy store.

2.

Calculate the kinetic energy of a 1000 kg car travelling at 15 m/s.

112,500 J

3.

Explain how energy is conserved but can be dissipated during energy transfers.

Energy is conserved because it is transferred between stores, but some energy is dissipated to the surroundings as heat or sound.

4.

A 2 kg object is raised 5 m. Calculate the gravitational potential energy gained if the gravitational field strength is 9.8 N/kg.

98 J

5.

Explain how efficiency calculations show how much energy is transferred usefully.

Efficiency calculations show the proportion of input energy transferred usefully.

6.

Compare renewable and non-renewable energy resources and explain their environmental impacts.

Renewable resources are sustainable and usually have fewer environmental impacts, while non-renewable resources can cause pollution and climate change.

4.2.1.1 Standard circuit diagram symbols

1.

Draw the circuit symbol used to represent a voltmeter.

Voltmeter – Circle with V inside.

2.

Draw the circuit symbol used to represent a resistor.

Resistor – Rectangle.

3.

Draw the circuit symbol used to represent a battery.

Battery – Two or more cells shown by alternating long and short parallel lines.

4.

Draw the circuit symbol used to represent an LED.

LED (Light Emitting Diode) – Diode symbol with two arrows pointing away from it.

5.

Draw the circuit symbol used to represent a thermistor.

Thermistor – Resistor symbol with a diagonal line and temperature marker.

6.

Draw a circuit diagram showing a cell, switch, lamp and resistor connected in series.

Series circuit: One cell connected in a single loop with a switch, lamp and resistor all in series.

4.2.1.2 Electrical charge and current

1.

What must a circuit contain for electrical charge to flow?

A complete closed circuit.

2.

What is meant by electric current?

The rate of flow of electric charge.

3.

A charge of 120 C flows through a circuit in 30 seconds. Calculate the current.

I = Q ÷ t = 120 ÷ 30 = 4 A

4.

A current of 5 A flows for 2 minutes. Calculate the charge transferred.

Q = I × t = 5 × 120 = 600 C

5.

A circuit transfers 600 C of charge in 3 minutes. Calculate the current.

3 minutes = 180 seconds
I = Q ÷ t = 600 ÷ 180 = 3.3 A

6.

Why does the current have the same value at any point in a single closed loop?

Because charge is not used up and cannot build up at any point in a series circuit.

4.2.1.3 Current, resistance and potential difference

1.

A resistor has a potential difference of 12 V across it and a current of 3 A flowing through it. Calculate its resistance.

R = V ÷ I = 12 ÷ 3 = 4 Ω

2.

A circuit has a resistance of 20 Ω and a current of 0.5 A. Calculate the potential difference across the component.

V = I × R = 0.5 × 20 = 10 V

3.

A lamp has a potential difference of 6 V and a resistance of 12 Ω. Calculate the current through the lamp.

I = V ÷ R = 6 ÷ 12 = 0.5 A

4.

How does increasing the resistance of a component affect the current for a fixed potential difference?

The current decreases.

5.

A student measures the resistance of wires with different lengths. The wire length increases from 0.5 m to 2.0 m. Describe the expected relationship between wire length and resistance.

Resistance increases as wire length increases.

6.

What happens to the current in a circuit if the potential difference is increased while resistance stays constant?

The current increases.

4.2.2 Series and parallel circuits

1.

What happens to the current in components connected in series?

The current is the same through every component.

2.

What happens to the potential difference across components connected in series?

The potential difference is shared between the components.

3.

Two resistors of 5 Ω and 10 Ω are connected in series. Calculate the total resistance.

Total resistance = 5 + 10 = 15 Ω

4.

A series circuit contains resistors of 8 Ω and 12 Ω. Calculate the total resistance.

Total resistance = 8 + 12 = 20 Ω

5.

What happens to the potential difference across components connected in parallel?

The potential difference is the same across each branch.

6.

Explain why adding resistors in parallel decreases the total resistance of a circuit.

More branches provide more paths for charge to flow, reducing the total resistance.

4.2.3.1 Direct and alternating potential difference

1.

What is the difference between direct and alternating potential difference?

Direct potential difference always acts in one direction. Alternating potential difference repeatedly changes direction.

2.

What type of potential difference is supplied by mains electricity in the UK?

Alternating current (AC).

3.

What is the frequency of the UK mains electricity supply?

50 Hz

4.

What is the approximate potential difference of the UK domestic electricity supply?

230 V

5.

Why are batteries described as providing direct potential difference?

Batteries provide a constant potential difference in one direction.

6.

Why does alternating potential difference change direction over time?

The direction of the current reverses many times each second.

4.2.3.2 Mains electricity

1.

What is the purpose of the live wire in a mains cable?

Carries the alternating potential difference into the appliance.

2.

What is the purpose of the neutral wire in a mains cable?

Completes the circuit by carrying current away from the appliance.

3.

What is the purpose of the earth wire in a mains cable?

Provides a safe path to Earth if a fault occurs.

4.

Why can a live wire be dangerous even when a switch is open?

The live wire is still connected to the supply and remains at a dangerous potential.

5.

Why is the earth wire important for electrical safety?

It prevents the metal case becoming live if a fault occurs.

6.

What are the colour codes used for the live, neutral and earth wires in mains cables?

Live = Brown, Neutral = Blue, Earth = Green/Yellow.

4.2.4.1 Power

1.

A device has a potential difference of 12 V and a current of 5 A. Calculate its power.

P = V × I = 12 × 5 = 60 W

2.

A motor has a current of 4 A and a resistance of 20 Ω. Calculate the power transferred.

P = I²R = 4² × 20 = 16 × 20 = 320 W

3.

A lamp transfers 600 W of power at a potential difference of 240 V. Calculate the current through the lamp.

I = P ÷ V = 600 ÷ 240 = 2.5 A

4.

How does increasing the current through a device affect the power transferred?

The power increases.

5.

How does increasing the potential difference across a device affect the power transferred?

The power increases.

6.

Explain how power describes the rate of energy transfer in an electrical device.

Power is the rate at which energy is transferred.

4.2.4.2 Energy transfers in everyday appliances

1.

A 1000 W heater is used for 60 seconds. Calculate the energy transferred.

E = P × t = 1000 × 60 = 60,000 J

2.

A device transfers 72 000 J of energy and has a power of 1200 W. Calculate the operating time.

t = E ÷ P = 72,000 ÷ 1200 = 60 s

3.

An appliance transfers 5000 J of energy using a charge flow of 20 C. Calculate the potential difference.

V = E ÷ Q = 5000 ÷ 20 = 250 V

4.

How do electrical appliances transfer energy from electrical stores to other energy stores?

Electrical energy is transferred to thermal, kinetic, light or sound energy stores.

5.

Why do higher power appliances transfer more energy in the same amount of time?

They transfer more energy every second.

6.

Describe the energy transfers that occur in an electric motor.

Electrical energy is transferred mainly to the kinetic energy store, with some energy dissipated as thermal energy and sound.

4.2.4.3 The National Grid

1.

What is the National Grid?

A network of cables and transformers that transfers electricity from power stations to consumers.

2.

Why are step-up transformers used in the National Grid?

To increase the potential difference and reduce the current.

3.

Why are step-down transformers used before electricity reaches homes?

To reduce the potential difference to a safe value before entering homes.

4.

Explain why electricity is transmitted at high potential differences.

A higher potential difference means a lower current for the same power, reducing energy lost by heating.

5.

How does the National Grid reduce energy losses during electricity transmission?

By transmitting electricity at high potential difference and low current.

6.

Describe how electricity is transferred from power stations to consumers.

Electricity is generated at power stations, stepped up by transformers, transmitted through the National Grid, stepped down before reaching consumers.

4.2.5.1 Static charge (Physics only)

1.

How can an insulating material become electrically charged?

By friction transferring electrons between insulating materials.

2.

Which particle is transferred when static electricity is produced?

Electrons.

3.

What charge does an object gain when it gains electrons?

A negative charge.

4.

What happens when two objects with the same type of charge are brought close together?

They repel.

5.

What happens when two objects with opposite charges are brought close together?

They attract.

6.

Why are attraction and repulsion between charged objects examples of non-contact forces?

Because the force acts without the objects touching.

4.2.5.2 Electric fields (Physics only)

1.

What is an electric field?

A region where a charged object experiences a force.

2.

Where is the electric field strongest around a charged object?

Closest to the charged object.

3.

How does the strength of an electric field change as distance from the charged object increases?

It decreases with distance.

4.

Why does a charged object placed in an electric field experience a force?

Because the electric field exerts a force on any charged object placed within it.

5.

Describe the electric field pattern around an isolated charged sphere.

Radial field lines pointing away from a positive charge or towards a negative charge.

6.

Explain how electric fields help to explain electrostatic forces between charged objects.

Electric fields explain the attractive and repulsive forces between charged objects.

Topic 2 Review

1.

A current of 3 A flows through a circuit for 5 minutes. Calculate the charge transferred.

Q = I × t = 3 × (5 × 60) = 3 × 300 = 900 C

2.

A resistor has a potential difference of 9 V and a resistance of 3 Ω. Calculate the current through the resistor.

I = V ÷ R = 9 ÷ 3 = 3 A

3.

Two resistors of 15 Ω and 25 Ω are connected in series. Calculate the total resistance.

Total resistance = 15 + 25 = 40 Ω

4.

A device uses a power of 1200 W for 30 seconds. Calculate the energy transferred.

E = P × t = 1200 × 30 = 36,000 J

5.

Explain why the National Grid uses high potential differences to transfer electrical energy.

High potential differences reduce the current, reducing energy lost as heat in the transmission cables.

6.

Explain how static electricity is produced and why charged objects can attract or repel each other.

Static electricity is produced by the transfer of electrons. Like charges repel and opposite charges attract.

4.3.1.1 Density of materials

1.

What is meant by the density of a material?

The mass per unit volume of a material.

2.

A metal block has a mass of 600 g and a volume of 200 cm³. Calculate the density of the metal block.

Density = Mass ÷ Volume = 600 g ÷ 200 cm³ = 3 g/cm³

3.

A liquid has a density of 800 kg/m³ and a volume of 0.005 m³. Calculate the mass of the liquid.

Mass = Density × Volume = 800 × 0.005 = 4 kg

4.

An object has a mass of 2 kg and a density of 400 kg/m³. Calculate the volume of the object.

Volume = Mass ÷ Density = 2 ÷ 400 = 0.005 m³

5.

Explain why solids usually have a higher density than gases using the particle model.

Solid particles are packed closely together, whereas gas particles are far apart.

6.

Describe how you would measure the density of an irregular solid object.

Measure the mass using a balance, measure the volume by water displacement in a measuring cylinder, then calculate Density = Mass ÷ Volume.

4.3.1.2 Changes of state

1.

What happens to the mass of a substance when it changes state?

The mass stays the same.

2.

Why are changes of state described as physical changes?

No new substance is formed, so it is a physical change.

3.

What happens to the particles of a substance when it melts?

The particles gain energy and move more freely as they overcome some of the forces between them.

4.

What happens to the particles of a substance when it freezes?

The particles lose energy, move more slowly and become fixed in position.

5.

Explain why a substance keeps the same mass when changing from a solid to a liquid.

No particles are lost or gained, so the mass remains constant.

6.

Describe the difference between evaporation and boiling.

Evaporation happens at the surface and can occur below the boiling point. Boiling happens throughout the liquid at a fixed temperature.

4.3.2.1 Internal energy

1.

What is meant by the internal energy of a system?

The total kinetic energy and potential energy of all the particles in a system.

2.

What two types of energy make up the internal energy of a system?

Kinetic energy and potential energy.

3.

How does heating a substance affect the energy stored by its particles?

The particles gain energy.

4.

What happens to the internal energy of a substance when its temperature increases?

The internal energy increases.

5.

Why can heating a substance cause either a temperature increase or a change of state?

Energy can either increase the kinetic energy of the particles (raising temperature) or increase their potential energy (changing state).

6.

Explain how the particle model describes internal energy.

Internal energy is the sum of the kinetic and potential energies of the particles.

4.3.2.2 Temperature changes in a system and specific heat capacity

1.

A 2 kg substance with a specific heat capacity of 400 J/kg°C is heated by 10°C. Calculate the energy transferred.

Energy = Mass × SHC × Temperature change = 2 × 400 × 10 = 8000 J

2.

A substance absorbs 6000 J of energy and has a mass of 3 kg. Its temperature increases by 5°C. Calculate its specific heat capacity.

SHC = Energy ÷ (Mass × Temperature change) = 6000 ÷ (3 × 5) = 6000 ÷ 15 = 400 J/kg°C

3.

A 5 kg block has a specific heat capacity of 900 J/kg°C and receives 45 000 J of energy. Calculate the temperature increase.

Temperature change = Energy ÷ (Mass × SHC) = 45,000 ÷ (5 × 900) = 45,000 ÷ 4500 = 10°C

4.

What factors affect the temperature increase of a substance when it is heated?

The mass, specific heat capacity and temperature change.

5.

What is meant by the specific heat capacity of a substance?

The energy needed to raise the temperature of 1 kg of a substance by 1°C.

6.

Why do different materials have different temperature increases when given the same amount of energy?

Different materials have different specific heat capacities, so they require different amounts of energy to raise their temperature.

4.3.2.3 Changes of state and specific latent heat

1.

What is meant by latent heat?

The energy needed to change the state of 1 kg of a substance without changing its temperature.

2.

What happens to the temperature of a substance while it is changing state?

The temperature remains constant.

3.

A substance has a mass of 2 kg and a specific latent heat of 300 000 J/kg. Calculate the energy needed to change its state.

Energy = Mass × Specific latent heat = 2 × 300,000 = 600,000 J

4.

A substance requires 900 000 J of energy to change state and has a mass of 3 kg. Calculate its specific latent heat.

Specific latent heat = Energy ÷ Mass = 900,000 ÷ 3 = 300,000 J/kg

5.

Explain the difference between specific heat capacity and specific latent heat.

Specific heat capacity changes temperature; specific latent heat changes state without changing temperature.

6.

Describe what happens to the internal energy of a substance during a change of state.

The internal energy increases because the potential energy of the particles increases while the kinetic energy remains constant.

4.3.3.1 Particle motion in gases

1.

How are gas molecules arranged and how do they move?

Gas particles are far apart and move rapidly in random directions.

2.

How is the temperature of a gas related to the average kinetic energy of its molecules?

The higher the temperature, the greater the average kinetic energy of the molecules.

3.

What happens to the pressure of a gas if its temperature increases while the volume stays constant?

The pressure increases.

4.

Explain why increasing the temperature of a gas increases the pressure.

The particles move faster and collide with the container walls more often and with greater force.

5.

Why do gas particles exert pressure on the walls of a container?

They collide with the walls of the container.

6.

Describe how the particle model explains the pressure of a gas.

Pressure is caused by gas particles colliding with the walls of the container.

4.3.3.2 Pressure in gases

1.

What happens to the pressure of a gas when its volume decreases at constant temperature?

The pressure increases.

2.

A gas has a volume of 4 m³ and a pressure of 100 000 Pa. Calculate the new pressure if the volume decreases to 2 m³.

Pressure₁ × Volume₁ = Pressure₂ × Volume₂
100,000 × 4 = Pressure₂ × 2
Pressure₂ = 400,000 ÷ 2 = 200,000 Pa

3.

A gas has a pressure of 200 000 Pa and a volume of 3 m³. Calculate the new volume if the pressure increases to 600 000 Pa.

Pressure₁ × Volume₁ = Pressure₂ × Volume₂
200,000 × 3 = 600,000 × Volume₂
Volume₂ = 600,000 ÷ 600,000 = 1 m³

4.

Explain why compressing a gas increases its pressure.

Gas particles collide with the container walls more frequently.

5.

Why does increasing the volume of a gas decrease its pressure at constant temperature?

The particles collide with the walls less often, so the pressure decreases.

6.

Describe how gas particles create a force on the walls of a container.

Gas particles collide with the walls, exerting a force. Pressure is the force per unit area.

4.3.3.3 Increasing the pressure of a gas (HT only)

1.

What happens to the internal energy of a gas when work is done on it?

Its internal energy increases.

2.

Explain why using a bicycle pump can increase the temperature of the gas inside it.

Work is done on the gas, increasing its internal energy and therefore its temperature.

3.

How does compressing a gas affect the movement of its particles?

The particles move faster.

4.

Why does doing work on a gas transfer energy to the gas?

Doing work transfers energy to the gas.

5.

Describe the energy transfers that occur when a gas is compressed.

Mechanical energy is transferred to the internal energy store of the gas.

6.

Explain why the temperature of an enclosed gas can increase when its pressure increases.

Increasing the pressure does work on the gas, increasing its internal energy and temperature.

Topic 3 Review

1.

A solid object has a mass of 3 kg and a volume of 0.002 m³. Calculate its density.

Density = Mass ÷ Volume = 3 ÷ 0.002 = 1500 kg/m³

2.

Explain how the particle arrangement changes when a substance melts.

Particles gain energy, overcome some of the forces between them and move more freely.

3.

A 4 kg substance with a specific heat capacity of 500 J/kg°C is heated by 20°C. Calculate the energy transferred.

Energy = Mass × SHC × Temperature change = 4 × 500 × 20 = 40,000 J

4.

Explain why the temperature remains constant during a change of state.

The energy supplied is used to change the state by increasing the particles' potential energy rather than increasing their kinetic energy.

5.

Describe how increasing the temperature of a gas affects its pressure when the volume is constant.

Increasing the temperature increases the kinetic energy of the gas particles, causing more frequent and forceful collisions with the container walls, so the pressure increases.

6.

Explain how doing work on a gas can increase its temperature.

Doing work on the gas transfers energy to its internal energy store, increasing the kinetic energy of the particles and therefore its temperature.

4.4.1.1 The structure of an atom

1.

What are the three main particles that make up an atom?

Protons, neutrons and electrons.

2.

Where is most of the mass of an atom concentrated?

In the nucleus.

3.

What is the charge of a proton, neutron and electron?

Proton = +1, Neutron = 0, Electron = −1.

4.

Describe the arrangement of electrons around the nucleus.

Electrons occupy shells (energy levels) around the nucleus.

5.

What happens to electrons when an atom absorbs electromagnetic radiation?

Electrons move to a higher energy level (shell).

6.

Why is the radius of the nucleus much smaller than the radius of the atom?

The nucleus is about 1/10,000 of the radius of the atom.

4.4.1.2 Mass number, atomic number and isotopes

1.

An atom has 8 protons and 8 neutrons. Calculate its atomic number and mass number.

Atomic number = 8, Mass number = 16.

2.

An atom has an atomic number of 12 and a mass number of 24. Calculate the number of neutrons.

Neutrons = Mass number − Atomic number = 24 − 12 = 12 neutrons.

3.

What is meant by the atomic number of an element?

The number of protons in the nucleus.

4.

What is meant by the mass number of an atom?

The total number of protons and neutrons in the nucleus.

5.

What are isotopes?

Atoms of the same element with the same number of protons but different numbers of neutrons.

6.

Explain how an atom becomes a positive ion.

By losing one or more electrons.

4.4.1.3 The development of the model of the atom

1.

Why did the discovery of the electron cause scientists to change the atomic model?

It showed atoms contained smaller particles and were not solid spheres.

2.

Describe the plum pudding model of the atom.

A sphere of positive charge with electrons embedded throughout.

3.

What did the alpha particle scattering experiment show about the structure of the atom?

Most of the atom is empty space with a small, dense, positively charged nucleus.

4.

How did the nuclear model differ from the plum pudding model?

The nuclear model had a tiny central nucleus with electrons around it instead of positive charge spread throughout the atom.

5.

What did Bohr suggest about the arrangement of electrons?

Electrons orbit the nucleus in fixed energy levels (shells).

6.

How did the discovery of neutrons change the model of the atom?

It explained the existence of isotopes and the extra mass of atoms.

4.4.2.1 Radioactive decay and nuclear radiation

1.

What is radioactive decay?

The spontaneous emission of radiation from an unstable nucleus.

2.

Why are some atomic nuclei unstable?

They have an unstable combination of protons and neutrons.

3.

What is meant by the activity of a radioactive source?

The number of nuclear decays per second.

4.

What particles make up an alpha particle?

Two protons and two neutrons.

5.

How is beta radiation produced?

A neutron changes into a proton and an electron is emitted.

6.

Compare the penetration and ionising power of alpha, beta and gamma radiation.

Alpha: most ionising, least penetrating (stopped by paper). Beta: medium ionising and penetrating (stopped by aluminium). Gamma: least ionising, most penetrating (stopped by lead/concrete).

4.4.2.2 Nuclear equations

1.

What happens to the mass number and atomic number during alpha decay?

Mass number decreases by 4 and atomic number decreases by 2.

2.

What happens to the mass number and atomic number during beta decay?

Mass number stays the same and atomic number increases by 1.

3.

A nucleus of uranium-238 undergoes alpha decay. Write the nuclear equation and state how the mass number and atomic number change.

²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He. Mass number −4, atomic number −2.

4.

A nucleus of carbon-14 undergoes beta decay. Write the nuclear equation and state how the mass number and atomic number change.

¹⁴₆C → ¹⁴₇N + ⁰₋₁e. Mass number unchanged, atomic number +1.

5.

Why does gamma radiation not change the mass number or atomic number?

Gamma radiation has no mass and no charge.

6.

Complete the nuclear equation: ²³⁸₉₂U → ²³⁴₉₀Th + _____

⁴₂He (alpha particle).

4.4.2.3 Half-lives and the random nature of radioactive decay

1.

What is meant by the half-life of a radioactive isotope?

The time taken for the activity (or number of undecayed nuclei) to halve.

2.

A radioactive sample has a count rate of 800 counts per minute. Calculate the count rate after two half-lives.

800 ÷ 2 = 400 counts/min after one half-life. 400 ÷ 2 = 200 counts/min after two half-lives.

3.

A radioactive sample has an initial activity of 1200 Bq and a half-life of 5 years. Calculate the activity after 10 years.

1200 ÷ 2 = 600 Bq after 5 years. 600 ÷ 2 = 300 Bq after 10 years.

4.

Why is radioactive decay described as a random process?

It is impossible to predict exactly when an individual nucleus will decay.

5.

How can the half-life of a radioactive isotope be found from a graph?

Measure the time taken for the activity (or count rate) to halve.

6.

Explain why the activity of a radioactive sample decreases over time.

There are fewer unstable nuclei remaining to decay.

4.4.2.4 Radioactive contamination

1.

What is meant by radioactive contamination?

The unwanted presence of radioactive material on or inside an object.

2.

What is meant by irradiation?

The exposure of an object to radiation.

3.

Explain the difference between contamination and irradiation.

Contamination involves radioactive material being transferred; irradiation does not.

4.

Why does radioactive contamination remain hazardous after the source is removed?

The radioactive material continues to emit radiation.

5.

Why does an irradiated object not become radioactive?

No radioactive material is transferred to the object.

6.

Why is peer review important when studying the effects of radiation?

It helps ensure scientific conclusions are checked for accuracy and reliability.

4.4.3.1 Background radiation

1.

What is background radiation?

Radiation that is always present in the environment.

2.

Name two natural sources of background radiation.

Radon gas and cosmic rays.

3.

Name two human-made sources of background radiation.

Medical X-rays and nuclear power stations.

4.

How can a person’s location affect their radiation dose?

Areas with more radon gas or higher altitude receive higher doses.

5.

How can a person’s occupation affect their radiation dose?

Jobs such as airline crew or nuclear industry workers may receive higher doses.

6.

What unit is used to measure radiation dose?

Sievert (Sv).

4.4.3.2 Different half-lives of radioactive isotopes

1.

Why do radioactive isotopes have different half-life values?

Different nuclei have different levels of stability.

2.

Explain why a radioactive isotope with a short half-life may be more hazardous.

It has a high activity because many nuclei decay each second.

3.

Explain why a radioactive isotope with a long half-life may remain hazardous for a long time.

It continues emitting radiation for a long time.

4.

How does half-life affect the choice of isotope for a specific use?

The half-life should suit the intended use.

5.

A radioactive isotope has a half-life of 10 years. What fraction remains after 30 years?

After one half-life = ½. After two = ¼. After three = ⅛ remains.

6.

Why must the half-life of a radioactive source be considered when assessing risk?

It determines how long the source remains hazardous.

4.4.3.3 Uses of nuclear radiation

1.

How are nuclear radiations used to explore internal organs?

Radioactive tracers detected outside the body.

2.

How can nuclear radiation be used to destroy unwanted tissue?

Radiotherapy using gamma radiation.

3.

Why are gamma rays useful for medical imaging?

They pass through the body and can be detected outside it.

4.

Why must the risks of using nuclear radiation be considered?

Radiation can damage healthy cells and increase cancer risk.

5.

Explain why radioactive tracers are useful in medicine.

They travel through the body and their movement can be detected.

6.

Evaluate one advantage and one disadvantage of using nuclear radiation in medicine.

Advantage: diagnose or treat disease. Disadvantage: exposure can damage healthy tissue.

4.4.4.1 Nuclear fission

1.

What is nuclear fission?

The splitting of a large unstable nucleus into two smaller nuclei.

2.

Why must a neutron be absorbed before fission usually occurs?

It makes the nucleus unstable enough to split.

3.

What happens when a large unstable nucleus undergoes fission?

It splits into two smaller nuclei, releases energy and emits two or three neutrons.

4.

What is a chain reaction in nuclear fission?

A self-sustaining series of fission reactions.

5.

How is a chain reaction controlled in a nuclear reactor?

Control rods absorb excess neutrons.

6.

Why does an uncontrolled chain reaction cause a nuclear explosion?

Neutrons cause rapid uncontrolled fission, releasing huge amounts of energy.

4.4.4.2 Nuclear fusion

1.

What is nuclear fusion?

Two light nuclei join together to form a heavier nucleus.

2.

What happens when two light nuclei undergo fusion?

They combine to form a larger nucleus.

3.

How can energy be released during nuclear fusion?

Some mass is converted into energy.

4.

Why is some mass converted into energy during fusion?

Because the mass of the products is less than the mass of the reactants, so the missing mass is transferred as energy.

5.

Compare nuclear fusion with nuclear fission.

Fusion joins small nuclei; fission splits large nuclei.

6.

Why is nuclear fusion difficult to achieve on Earth?

Extremely high temperatures and pressures are needed to overcome electrostatic repulsion.

Topic 4 Review

1.

An atom contains 17 protons and 18 neutrons. Calculate its atomic number and mass number.

Atomic number = 17, Mass number = 35.

2.

Explain how the alpha particle scattering experiment changed the model of the atom.

It showed that atoms contain a small, dense, positively charged nucleus and are mostly empty space.

3.

A radioactive sample has an activity of 1600 Bq. Calculate its activity after three half-lives.

1600 ÷ 2 = 800 Bq. 800 ÷ 2 = 400 Bq. 400 ÷ 2 = 200 Bq after three half-lives.

4.

Compare alpha, beta and gamma radiation in terms of penetration and ionising ability.

Alpha: highly ionising, least penetrating. Beta: medium ionising and penetrating. Gamma: weakly ionising, most penetrating.

5.

Explain the difference between nuclear fission and nuclear fusion.

Fission splits large nuclei; fusion joins small nuclei. Both release energy.

6.

Explain how radioactive isotopes can be useful but also hazardous.

Radioactive isotopes are useful in medicine and industry but can damage living tissue through ionising radiation.

4.5.1.1 Scalar and vector quantities

1.

A car travels 500 m along a straight road. Is this distance a scalar or vector quantity?

Scalar quantity.

2.

A force of 20 N acts to the right on an object. Explain why this force is a vector quantity.

Because it has both magnitude (20 N) and direction (to the right).

3.

A runner completes one lap of a 400 m track and finishes where they started. What is the runner’s displacement?

0 m

4.

A force is represented by an arrow. Explain what the length and direction of the arrow represent.

The length represents the size (magnitude) of the force and the arrow shows its direction.

5.

Classify each quantity as scalar or vector: speed, velocity, distance, displacement.

Speed – Scalar; Velocity – Vector; Distance – Scalar; Displacement – Vector.

6.

A student walks 10 m north and then 10 m south. Calculate the total distance travelled and the displacement.

Distance = 10 + 10 = 20 m. Displacement = 0 m.

4.5.1.2 Contact and non-contact forces

1.

Explain the difference between a contact force and a non-contact force.

A contact force acts when objects are touching. A non-contact force acts without the objects touching.

2.

Identify the type of force involved when a book rests on a table.

Contact force (normal contact force).

3.

A magnet attracts a paper clip without touching it. Is this a contact or non-contact force? Explain your answer.

Non-contact force because the magnet attracts the paper clip without touching it.

4.

Give two examples of contact forces and two examples of non-contact forces.

Contact forces: friction, air resistance. Non-contact forces: gravitational force, magnetic force.

5.

Explain the forces acting between a person pushing a shopping trolley and the trolley.

The person pushes the trolley forwards and the trolley pushes back on the person with an equal and opposite force.

6.

A skydiver is falling through the air. Identify the contact and non-contact forces acting on the skydiver.

Contact force: air resistance. Non-contact force: gravitational force (weight).

4.5.1.3 Gravity

1.

Calculate the weight of a 5 kg object on Earth where the gravitational field strength is 10 N/kg.

Weight = Mass × Gravitational field strength = 5 × 10 = 50 N

2.

An object has a weight of 98 N on Earth. Calculate its mass.

Mass = Weight ÷ Gravitational field strength = 98 ÷ 9.8 = 10 kg

3.

A person has a mass of 60 kg. Calculate their weight on Earth using a gravitational field strength of 9.8 N/kg.

Weight = Mass × Gravitational field strength = 60 × 9.8 = 588 N

4.

Explain why the weight of an object changes when it is taken to a different planet.

Because gravitational field strength is different on different planets.

5.

A 2 kg object is taken to a planet with a gravitational field strength of 5 N/kg. Calculate its weight.

Weight = Mass × Gravitational field strength = 2 × 5 = 10 N

6.

Explain why an object’s mass stays the same while its weight can change.

Mass is the amount of matter in an object and does not change. Weight depends on gravitational field strength.

4.5.1.4 Resultant forces

1.

Two forces act on an object in the same direction. One force is 10 N and the other is 15 N. Calculate the resultant force.

Resultant force = 10 + 15 = 25 N

2.

Two forces act on an object in opposite directions. One force is 30 N to the right and one is 20 N to the left. Calculate the resultant force.

Resultant force = 30 − 20 = 10 N to the right

3.

Explain what happens to an object when the resultant force acting on it is zero.

It remains at rest or continues moving at constant velocity.

4.

A car has a driving force of 5000 N and resistive forces of 5000 N. Describe the motion of the car.

The car moves at a constant speed.

5.

An object has a resultant force of 50 N acting on it. Explain what this tells you about the forces acting on the object.

There is an unbalanced force causing the object's velocity to change.

6.

A force of 100 N is split into two perpendicular components. Explain why the two components have the same effect as the original force.

Together, the two perpendicular components have the same overall effect as the single original force.

4.5.2 Work done and energy transfer

1.

A force of 50 N moves an object 4 m in the direction of the force. Calculate the work done.

Work done = Force × Distance = 50 × 4 = 200 J

2.

A machine does 3000 J of work while moving an object 10 m. Calculate the force applied.

Force = Work done ÷ Distance = 3000 ÷ 10 = 300 N

3.

A force of 200 N moves an object 5 m. Calculate the energy transferred.

Energy transferred = Work done = Force × Distance = 200 × 5 = 1000 J

4.

Explain why work is not done when a force is applied but an object does not move.

No work is done because there is no movement in the direction of the force.

5.

A box is pushed across the floor and friction causes the box to warm up. Explain the energy transfer involved.

Energy is transferred from the kinetic energy store to the thermal energy stores of the box and the floor due to friction.

6.

A force of 20 N moves an object 3 m. Calculate the work done in joules.

Work done = Force × Distance = 20 × 3 = 60 J

4.5.3 Forces and elasticity

1.

A spring extends by 0.04 m when a force of 8 N is applied. Calculate the spring constant.

Spring constant = Force ÷ Extension = 8 ÷ 0.04 = 200 N/m

2.

A spring has a spring constant of 250 N/m and extends by 0.02 m. Calculate the force applied.

Force = Spring constant × Extension = 250 × 0.02 = 5 N

3.

Explain the difference between elastic deformation and inelastic deformation.

Elastic deformation is reversible. Inelastic deformation is permanent.

4.

A spring stores 0.5 J of elastic potential energy when stretched by 0.1 m. Calculate the spring constant.

Elastic potential energy = ½ × Spring constant × Extension²
0.5 = ½ × k × (0.1)²
0.5 = ½ × k × 0.01
0.5 = 0.005k
k = 0.5 ÷ 0.005 = 100 N/m

5.

Explain what happens to the elastic potential energy stored in a spring when it is stretched further.

The elastic potential energy increases.

6.

Describe how you could investigate the relationship between force and extension for a spring.

Suspend a spring from a clamp stand, add known masses one at a time, measure the extension after each mass is added, calculate the force (Weight = mass × gravitational field strength), and plot a graph of force against extension.

4.5.4 Moments, levers and gears

1.

A force of 20 N acts 0.5 m from a pivot. Calculate the moment produced.

Moment = Force × Distance = 20 × 0.5 = 10 Nm

2.

A force produces a moment of 100 Nm at a distance of 2 m from a pivot. Calculate the force.

Force = Moment ÷ Distance = 100 ÷ 2 = 50 N

3.

Explain why increasing the distance from a pivot increases the turning effect of a force.

Because the moment equals force × distance from the pivot, so increasing the distance increases the turning effect.

4.

A balanced object has a clockwise moment of 60 Nm. Calculate the anticlockwise moment.

60 Nm

5.

Explain how a lever makes it easier to turn or lift an object.

A lever increases the distance from the pivot, increasing the moment so less force is needed.

6.

Explain how gears can change the rotational effect of forces.

Gears can increase or decrease the turning effect and change the speed and direction of rotation.

4.5.5.1 Pressure in a fluid 1

1.

What is a fluid?

A substance that can flow (a liquid or a gas).

2.

A force of 200 N acts over an area of 4 m². Calculate the pressure produced.

Pressure = Force ÷ Area = 200 ÷ 4 = 50 Pa

3.

A pressure of 500 Pa acts over an area of 2 m². Calculate the force applied.

Force = Pressure × Area = 500 × 2 = 1000 N

4.

In which direction does pressure in a fluid act on a surface?

At right angles (perpendicular) to the surface.

5.

What is the unit of pressure?

Pascal (Pa).

6.

Why does pressure in a fluid act at right angles to a surface?

Because fluid particles collide with surfaces equally in all directions.

4.5.5.1.2 Pressure in a fluid 2 (HT)

1.

A liquid has a density of 1000 kg/m³ and a depth of 5 m. Calculate the pressure due to the liquid if g = 10 N/kg.

Pressure = Height × Density × Gravitational field strength = 5 × 1000 × 10 = 50,000 Pa

2.

Why does pressure increase as the depth of a liquid increases?

Because there is more liquid above, producing a greater weight.

3.

Why does a denser liquid produce a greater pressure at the same depth?

A denser liquid has more mass per unit volume, so it exerts a greater pressure.

4.

A diver swims deeper underwater. Explain why the pressure on the diver increases.

The deeper the diver goes, the greater the weight of water above them, so the pressure increases.

5.

What is meant by upthrust?

The upward force exerted by a fluid on an object.

6.

Explain why an object partially submerged in water experiences an upward force.

Pressure is greater at the bottom of the object than at the top, producing a resultant upward force.

4.5.5.2 Atmospheric pressure

1.

Explain why atmospheric pressure decreases as altitude increases.

There are fewer air molecules above you at higher altitudes.

2.

Explain how air molecules create atmospheric pressure.

Air molecules collide with surfaces, producing a force per unit area.

3.

A mountain climber reaches a higher altitude. Explain how the number of air molecules above them changes.

The number of air molecules above them decreases.

4.

Explain why atmospheric pressure is greater at sea level than on top of a mountain.

There is a greater weight of air above sea level.

5.

Explain why atmospheric pressure is lower on a hill than at the bottom of a deep cave.

There are fewer air molecules above a hill than above a deep cave, so atmospheric pressure is lower.

6.

Explain why objects are not crushed by atmospheric pressure.

Because the pressure inside the body balances the atmospheric pressure outside.

4.5.6.1.1 Distance and displacement

1.

Explain the difference between distance and displacement.

Distance is the total path travelled. Displacement is the shortest straight-line distance in a given direction.

2.

A runner travels 500 m around a track and finishes where they started. Calculate their displacement.

0 m

3.

A person walks 200 m east. State their distance and displacement.

Distance = 200 m. Displacement = 200 m east.

4.

Explain why displacement is a vector quantity.

Because it has both magnitude and direction.

5.

A cyclist travels 3 km north then 1 km south. Calculate the total distance travelled.

Distance = 3 + 1 = 4 km

6.

A car travels from one town to another in a straight line. Explain why its displacement includes direction.

Because displacement includes both the distance and the direction from the starting point.

4.5.6.1.2 Speed

1.

A car travels 120 m in 10 s. Calculate its speed.

Speed = Distance ÷ Time = 120 ÷ 10 = 12 m/s

2.

A cyclist travels at 6 m/s for 30 seconds. Calculate the distance travelled.

Distance = Speed × Time = 6 × 30 = 180 m

3.

A runner covers 400 m in 80 seconds. Calculate their average speed.

Average speed = Distance ÷ Time = 400 ÷ 80 = 5 m/s

4.

Explain why speed is a scalar quantity.

Because it has magnitude only and no direction.

5.

A sound wave travels at 330 m/s for 5 seconds. Calculate the distance travelled.

Distance = Speed × Time = 330 × 5 = 1650 m

6.

Explain why a car travelling around a corner can have constant speed but changing velocity.

Its speed stays the same, but its direction changes, so its velocity changes.

4.5.6.1.3 Velocity

1.

Explain the difference between speed and velocity.

Speed is a scalar quantity. Velocity is a vector quantity (speed in a given direction).

2.

A car travels at 20 m/s east. Explain why this is a velocity.

Because it has both a magnitude (20 m/s) and a direction (east).

3.

Explain why an object moving in a circle can have constant speed but changing velocity.

Its direction is constantly changing, so its velocity changes even if its speed stays the same.

4.

A plane travels at 250 m/s north. Identify the speed and direction.

Speed = 250 m/s. Direction = north.

5.

Explain why velocity is a vector quantity.

Because it has both magnitude and direction.

6.

A runner changes direction while keeping the same speed. Explain what happens to their velocity.

Its velocity changes because its direction changes.

4.5.6.1.4 Distance-time relationship

1.

A car travels 200 m in 20 seconds. Calculate the speed from the distance-time graph information.

Speed = Distance ÷ Time = 200 ÷ 20 = 10 m/s

2.

Explain what a horizontal line on a distance-time graph represents.

The object is stationary.

3.

Explain what a steeper gradient on a distance-time graph shows.

The object is travelling faster.

4.

A distance-time graph has a straight line with a constant gradient. Describe the motion.

The object is moving at a constant speed.

5.

Explain how the speed of an object can be found from a distance-time graph.

Calculate the gradient (slope) of the graph.

6.

A cyclist’s distance-time graph becomes steeper. Explain what happens to the cyclist’s speed.

The cyclist's speed increases.

4.5.6.1.5 Acceleration

1.

A car increases its velocity from 10 m/s to 30 m/s in 5 seconds. Calculate its acceleration.

Acceleration = (Final velocity − Initial velocity) ÷ Time = (30 − 10) ÷ 5 = 20 ÷ 5 = 4 m/s²

2.

A vehicle slows from 25 m/s to 5 m/s in 4 seconds. Calculate its acceleration.

Acceleration = (5 − 25) ÷ 4 = −20 ÷ 4 = −5 m/s²

3.

Explain what negative acceleration means.

The object is slowing down (decelerating).

4.

A car accelerates at 3 m/s² for 10 seconds from rest. Calculate its final velocity.

Final velocity = Initial velocity + (Acceleration × Time) = 0 + (3 × 10) = 30 m/s

5.

Explain how acceleration can be found from a velocity-time graph.

Calculate the gradient (slope) of the velocity-time graph.

6.

Explain what the area under a velocity-time graph represents.

The distance travelled.

4.5.6.2.1 Newton’s First Law

1.

State Newton’s First Law of motion.

An object will remain at rest or continue moving at constant velocity unless acted on by a resultant force.

2.

What happens to an object if the resultant force acting on it is zero?

It remains at rest or continues moving at constant velocity.

3.

A car travels at a constant speed. What does this tell you about the forces acting on it?

The resultant force is zero (the forces are balanced).

4.

What is meant by inertia?

The tendency of an object to continue in its current state of motion.

5.

Why does a passenger move forwards when a car brakes suddenly?

Because their body continues moving forwards due to inertia.

6.

What causes an object’s velocity to change?

A resultant force.

4.5.6.2.2 Newton’s Second Law

1.

State Newton’s Second Law of motion.

The acceleration of an object is proportional to the resultant force and inversely proportional to its mass (F = ma).

2.

A force of 20 N acts on a 5 kg object. Calculate the acceleration.

Acceleration = Force ÷ Mass = 20 ÷ 5 = 4 m/s²

3.

An object accelerates at 4 m/s² when a force of 12 N acts on it. Calculate its mass.

Mass = Force ÷ Acceleration = 12 ÷ 4 = 3 kg

4.

How does increasing the mass of an object affect its acceleration for the same force?

Its acceleration decreases.

5.

What is inertial mass?

A measure of how difficult it is to change an object's velocity.

6.

Why is a larger force needed to accelerate a heavier vehicle?

Because it has a greater mass (greater inertial mass), so more force is needed to produce the same acceleration.

4.5.6.2.3 Newton’s Third Law

1.

State Newton’s Third Law of motion.

When two objects interact, they exert equal and opposite forces on each other.

2.

A swimmer pushes water backwards. Explain why the swimmer moves forwards.

The swimmer pushes the water backwards and the water pushes the swimmer forwards with an equal and opposite force.

3.

A rocket pushes gases downwards. Explain why the rocket moves upwards.

The rocket pushes gases downwards and the gases push the rocket upwards with an equal and opposite force.

4.

What are the sizes of the forces in a Newton’s Third Law pair?

They are equal in size.

5.

What directions do Newton’s Third Law forces act in?

They act in opposite directions.

6.

Why do Newton’s Third Law forces not cancel each other out?

Because they act on different objects, not the same object.

4.5.6.3.1 Stopping distance

1.

What two distances make up the stopping distance of a vehicle?

Thinking distance and braking distance.

2.

What is meant by thinking distance?

The distance travelled during the driver's reaction time.

3.

What is meant by braking distance?

The distance travelled from when the brakes are applied until the vehicle stops.

4.

Why does increasing vehicle speed increase stopping distance?

The thinking distance and braking distance both increase.

5.

A driver has a reaction time of 0.5 seconds. Explain how this affects stopping distance.

The car travels further before the brakes are applied, increasing the thinking distance.

6.

Why must drivers leave larger gaps at higher speeds?

Because both the thinking distance and braking distance are greater.

4.5.6.3.2 Reaction time

1.

What is the typical range of human reaction times?

0.2–0.9 seconds

2.

Name two factors that can increase a driver’s reaction time.

Tiredness and alcohol (or drugs).

3.

Describe one method used to measure reaction time.

Catching a falling ruler and measuring the distance it falls before being caught.

4.

Why can distractions increase stopping distance?

They increase the driver's reaction time, increasing the thinking distance.

5.

Explain how tiredness affects driving safety.

It increases reaction time, increasing the thinking distance and stopping distance.

6.

Why is reaction time different between individuals?

People have different ages, levels of tiredness, fitness and concentration.

4.5.6.3.3 Factors affecting braking distance 1

1.

Name two road conditions that increase braking distance.

Wet roads and icy roads.

2.

How do wet roads affect braking distance?

They reduce friction between the tyres and the road, increasing braking distance.

3.

How do worn tyres affect braking distance?

They provide less grip, increasing braking distance.

4.

Why does a greater speed increase braking distance?

The vehicle has more kinetic energy, so more work must be done to stop it.

5.

Why do vehicles need longer stopping distances in icy conditions?

There is very little friction between the tyres and the road.

6.

Explain why checking vehicle brakes improves safety.

Effective brakes produce greater friction, reducing braking distance.

4.5.6.3.4 Factors affecting braking distance 2

1.

What type of energy is reduced when brakes are applied?

The kinetic energy store.

2.

Explain why brakes become hotter when a vehicle stops.

Friction transfers kinetic energy to the thermal energy stores of the brakes and surroundings.

3.

Why does a greater vehicle speed require a greater braking force?

More kinetic energy must be removed, requiring a greater braking force.

4.

What problems can large decelerations cause?

They can cause loss of control or injury to passengers.

5.

Explain why friction is important when braking.

Friction provides the force needed to slow the vehicle.

6.

Why can overheating brakes reduce vehicle safety?

Overheated brakes are less effective because friction is reduced (brake fade).

4.5.7.1 Momentum is a property of moving objects (HT)

1.

What is momentum?

Momentum is the product of an object's mass and velocity.

2.

A 5 kg object travels at 4 m/s. Calculate its momentum.

Momentum = Mass × Velocity = 5 × 4 = 20 kg m/s

3.

A car has a momentum of 6000 kg m/s and a mass of 1000 kg. Calculate its velocity.

Velocity = Momentum ÷ Mass = 6000 ÷ 1000 = 6 m/s

4.

What unit is used for momentum?

kg m/s

5.

How does increasing the mass of an object affect its momentum at the same velocity?

Its momentum increases.

6.

How does increasing velocity affect momentum?

Its momentum increases.

4.5.7.2 Conservation of momentum (HT)

1.

State the principle of conservation of momentum.

In a closed system, the total momentum before an interaction equals the total momentum after the interaction.

2.

What is meant by a closed system?

A system where no external forces act.

3.

Two objects collide in a closed system. What happens to the total momentum before and after the collision?

The total momentum remains the same.

4.

Why is momentum useful when analysing collisions?

It allows the motion of objects before and after collisions to be analysed.

5.

What happens to the momentum of one object if another object gains momentum in the opposite direction?

The other object gains equal momentum in the opposite direction.

6.

Explain why total momentum is conserved during a collision.

Because no external forces act on the system.

4.5.7.3 Changes in momentum (HT)

1.

What happens to momentum when a force acts on a moving object?

Its momentum changes.

2.

Why do airbags reduce injuries during a collision?

They increase the time taken for the change in momentum, reducing the force on the passenger.

3.

How does increasing the time taken for a change in momentum affect the force produced?

The force decreases.

4.

Explain why crash mats reduce injuries.

They increase the time taken to stop, reducing the force on the person.

5.

A car changes momentum over a longer time because of crumple zones. Why does this reduce force?

The longer time taken to change momentum reduces the force acting on the car and passengers.

6.

Explain how seat belts reduce injuries using the idea of rate of change of momentum.

Seat belts increase the time taken for the passenger's momentum to change, reducing the force acting on them.

Topic 5 Review

1.

Explain the difference between scalar and vector quantities and give one example of each.

A scalar has magnitude only (e.g. speed). A vector has magnitude and direction (e.g. velocity).

2.

A 1200 kg car travels at 15 m/s. Calculate its kinetic effect in terms of momentum.

Momentum = Mass × Velocity = 1200 × 15 = 18,000 kg m/s

3.

Explain how Newton’s three laws describe the motion of objects.

Newton's First Law: Objects remain at rest or move at constant velocity unless acted on by a resultant force. Newton's Second Law: F = ma. Newton's Third Law: Forces occur in equal and opposite pairs.

4.

A force of 40 N moves an object 5 m. Calculate the work done.

Work done = Force × Distance = 40 × 5 = 200 J

5.

Explain why increasing speed increases stopping distance and braking safety risks.

Higher speeds increase both thinking distance and braking distance because the vehicle has more kinetic energy, increasing the stopping distance and risk of collisions.

6.

Compare contact forces, non-contact forces and their effects on objects.

Contact forces act when objects touch (e.g. friction, air resistance). Non-contact forces act at a distance (e.g. gravity, magnetic force). Both can change an object's motion.

4.6.1.1 Transverse and longitudinal waves

1.

Explain the difference between transverse and longitudinal waves.

In a transverse wave, vibrations are perpendicular to the direction of energy transfer. In a longitudinal wave, vibrations are parallel to the direction of energy transfer.

2.

State one example of a transverse wave.

Light (electromagnetic) waves.

3.

State one example of a longitudinal wave.

Sound waves.

4.

Describe the compressions and rarefactions in a longitudinal wave.

Compressions are regions where particles are close together. Rarefactions are regions where particles are spread apart.

5.

Explain why sound waves in air are longitudinal waves.

Because the air particles vibrate parallel to the direction of energy transfer.

6.

Explain why energy is transferred by a wave but the medium itself is not.

The particles vibrate about a fixed position, transferring energy to neighbouring particles without the medium moving overall.

4.6.1.2 Properties of waves

1.

Define the amplitude of a wave.

The maximum displacement of a point on a wave from its rest position.

2.

Define the wavelength of a wave.

The distance between two corresponding points on adjacent waves.

3.

A wave has a frequency of 25 Hz and a wavelength of 2 m. Calculate its wave speed.

Wave speed = Frequency × Wavelength = 25 × 2 = 50 m/s

4.

A wave travels at 300 m/s and has a frequency of 150 Hz. Calculate its wavelength.

Wavelength = Wave speed ÷ Frequency = 300 ÷ 150 = 2 m

5.

Calculate the period of a wave with a frequency of 50 Hz.

Period = 1 ÷ Frequency = 1 ÷ 50 = 0.02 s

6.

Describe how you could measure the speed of sound in air.

Measure the distance travelled by the sound and the time taken, then calculate speed = distance ÷ time.

4.6.1.3 Reflection of waves (Physics only)

1.

State what happens when a wave is reflected.

The wave bounces off the surface.

2.

Explain the difference between reflection, absorption and transmission.

Reflection: the wave bounces back. Absorption: the wave's energy is taken in by the material. Transmission: the wave passes through the material.

3.

Draw or describe a ray diagram showing reflection from a plane surface.

Angle of incidence = angle of reflection.

4.

Explain why some materials reflect more waves than others.

Smooth, hard surfaces absorb less energy and reflect more.

5.

Give one example where wave reflection is useful.

Mirrors.

6.

Explain why smooth surfaces produce regular reflection.

Because the surface is smooth, reflected rays remain parallel.

4.6.1.4 Sound waves (Physics only, HT)

1.

Explain how sound travels through a solid.

Particles in the solid vibrate and pass the vibrations to neighbouring particles.

2.

Describe how sound waves allow humans to hear.

Sound waves make the eardrum vibrate, producing electrical impulses sent to the brain.

3.

State the normal range of human hearing.

20 Hz to 20,000 Hz (20 kHz)

4.

Explain why humans cannot hear ultrasound.

Because its frequency is above 20,000 Hz.

5.

Explain why sound is transferred by vibrations.

Sound is produced by vibrating objects, which cause neighbouring particles to vibrate.

6.

Give one example of a process that converts sound waves into vibrations in a solid.

Seismic waves travelling through rock.

4.6.1.5 Waves for detection and exploration (Physics only, HT)

1.

State what is meant by ultrasound.

Sound waves with frequencies above 20,000 Hz.

2.

Explain how ultrasound can be used to produce a medical image.

Ultrasound pulses are reflected by different tissues and the echoes are used to produce an image.

3.

Explain how echo sounding is used to measure water depth.

Measure the time taken for an ultrasound pulse to return from the seabed and calculate the depth.

4.

State the difference between P-waves and S-waves.

P-waves are longitudinal and travel through solids and liquids. S-waves are transverse and travel only through solids.

5.

Explain why S-waves cannot travel through liquids.

Liquids cannot transmit transverse waves.

6.

Explain how seismic waves provide evidence for the structure of the Earth's core.

The absence of S-waves and changes in P-waves show that the Earth's outer core is liquid.

4.6.2.1 Types of electromagnetic waves

1.

State the seven types of electromagnetic wave in order from longest wavelength to shortest wavelength.

Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays.

2.

Explain why all electromagnetic waves are transverse waves.

Their oscillations are perpendicular to the direction of energy transfer.

3.

State the speed of electromagnetic waves in a vacuum.

3 × 10⁸ m/s

4.

Explain how electromagnetic waves transfer energy.

By carrying energy from one place to another.

5.

Which part of the electromagnetic spectrum can the human eye detect?

Visible light.

6.

Give one example of energy being transferred by an electromagnetic wave.

Sunlight transferring energy to the Earth.

4.6.2.2 Properties of electromagnetic waves 1

1.

Explain what happens to electromagnetic waves when they are refracted.

They change direction when entering a different medium.

2.

Explain why refraction occurs when a wave enters a different medium.

Because their speed changes.

3.

Describe how the speed of an electromagnetic wave changes when it enters a different substance.

It usually decreases in denser media.

4.

Draw or describe a ray diagram showing refraction.

The ray bends towards or away from the normal depending on the change in speed.

5.

Explain how wavefront diagrams can be used to explain refraction.

They show one side of the wave slowing before the other, causing the wave to bend.

6.

Describe the required practical investigating how different surfaces absorb infrared radiation.

Heat identical cans with different surface finishes using infrared radiation and measure the temperature increase.

4.6.2.3 Properties of electromagnetic waves 2

1.

Explain how radio waves can be produced.

By oscillating electrons in an electrical circuit.

2.

State where gamma rays originate.

From changes within the nucleus of radioactive atoms.

3.

Explain why ultraviolet, X-rays and gamma rays can be harmful to humans.

They are ionising and can damage cells and DNA.

4.

Explain what is meant by ionising radiation.

Radiation that removes electrons from atoms.

5.

State one effect of ultraviolet radiation on the human body.

Sunburn.

6.

Explain why exposure to large doses of X-rays or gamma rays increases the risk of cancer.

Ionising radiation can damage DNA, increasing the chance of mutations and cancer.

4.6.2.4 Uses and applications of electromagnetic waves

1.

State one use of radio waves.

Radio broadcasting.

2.

Explain why microwaves are suitable for satellite communications.

They pass through the Earth's atmosphere and carry information over long distances.

3.

State one use of infrared radiation.

Thermal imaging (or TV remote controls).

4.

Explain why visible light is used in fibre optic communication.

It undergoes total internal reflection with little energy loss.

5.

State one medical use of X-rays or gamma rays.

X-rays for medical imaging (or gamma rays for cancer treatment).

6.

Explain why different electromagnetic waves are suitable for different applications.

Different electromagnetic waves have different properties, making them suitable for different uses.

4.6.2.5 Lenses (Physics only)

1.

Explain how a convex lens forms an image.

A convex lens refracts light rays so they meet at a focus to form an image.

2.

State the difference between a convex lens and a concave lens.

A convex lens converges light. A concave lens diverges light.

3.

Define the focal length of a lens.

The distance from the centre of the lens to the principal focus.

4.

An object is 4 cm high and its image is 12 cm high. Calculate the magnification.

Magnification = Image height ÷ Object height = 12 ÷ 4 = 3

5.

Explain the difference between a real image and a virtual image.

A real image can be projected onto a screen. A virtual image cannot.

6.

Describe how you could investigate the magnification produced by convex lenses.

Measure the object and image heights for different object distances and calculate magnification.

4.6.2.6 Visible light (Physics only)

1.

Explain the difference between specular reflection and diffuse reflection.

Specular reflection occurs from smooth surfaces. Diffuse reflection occurs from rough surfaces.

2.

Explain how a colour filter works.

It transmits its own colour and absorbs the other colours.

3.

Explain why a red object appears red in white light.

It reflects red light and absorbs the other colours.

4.

Explain why a white object appears white.

It reflects all colours of visible light.

5.

State the difference between transparent and translucent materials.

Transparent materials allow light through clearly. Translucent materials allow some light through but scatter it.

6.

Explain what colour a black object appears and why.

It appears black because it absorbs nearly all visible light.

4.6.3.1 Emission and absorption of infrared radiation

1.

State what all objects emit, regardless of their temperature.

Infrared radiation.

2.

Explain how the amount of infrared radiation emitted changes as temperature increases.

The hotter the object, the more infrared radiation it emits.

3.

Define a perfect black body.

An object that absorbs all incident electromagnetic radiation.

4.

Explain why a perfect black body is also the best emitter of infrared radiation.

Good absorbers are also good emitters.

5.

Explain why a shiny surface is a poor absorber of infrared radiation.

It reflects most infrared radiation instead of absorbing it.

6.

State which type of surface is best at absorbing infrared radiation.

A matt black surface.

4.6.3.2 Perfect black bodies and radiation

1.

Explain why all objects emit electromagnetic radiation.

Because all objects above absolute zero emit infrared radiation.

2.

Explain how the radiation emitted by an object depends on its temperature.

As temperature increases, the rate of emission increases.

3.

Explain what happens when an object absorbs radiation faster than it emits radiation.

Its temperature increases.

4.

Explain what happens when an object is at a constant temperature.

It emits energy at the same rate as it absorbs energy.

5.

Explain how the Earth's temperature depends on the balance between absorbed and emitted radiation.

It depends on the balance between incoming solar radiation and outgoing infrared radiation.

6.

Explain why increasing reflection of radiation into space can reduce the Earth's temperature.

More energy is reflected into space, so less is absorbed by the Earth, reducing its temperature.

Topic 6 Review

1.

Explain the difference between transverse and longitudinal waves and give one example of each.

Transverse waves vibrate perpendicular to the direction of energy transfer (e.g. light). Longitudinal waves vibrate parallel to the direction of energy transfer (e.g. sound).

2.

A wave has a frequency of 200 Hz and a wavelength of 1.5 m. Calculate its wave speed.

Wave speed = Frequency × Wavelength = 200 × 1.5 = 300 m/s

3.

Compare ultrasound, seismic waves and electromagnetic waves, giving one use for each.

Ultrasound – medical imaging. Seismic waves – studying the Earth's structure. Electromagnetic waves – communication (e.g. radio waves).

4.

Explain why different parts of the electromagnetic spectrum are used for different applications.

Different parts of the electromagnetic spectrum have different properties such as penetration and wavelength, making them suitable for different applications.

5.

A convex lens forms an image three times larger than the object. Calculate the magnification.

Magnification = 3

6.

Explain how the balance between absorbed and emitted radiation affects the temperature of the Earth.

If the Earth absorbs more radiation than it emits, its temperature increases. If it emits more than it absorbs, its temperature decreases.

4.7.1.1 Poles of a magnet

1.

Explain why the magnetic forces are strongest at the poles of a magnet.

Because the magnetic field is strongest at the poles.

2.

Describe what happens when two north poles of permanent magnets are brought close together.

They repel each other.

3.

Describe what happens when a north pole and a south pole of permanent magnets are brought close together.

They attract each other.

4.

Explain the difference between a permanent magnet and an induced magnet.

A permanent magnet produces its own magnetic field. An induced magnet only becomes magnetic in an external magnetic field.

5.

Explain why an induced magnet always attracts a permanent magnet.

The induced pole nearest the permanent magnet is always the opposite pole.

6.

Explain what happens to an induced magnet when it is removed from a magnetic field.

It usually loses its magnetism.

4.7.1.2 Magnetic fields

1.

Define the magnetic field surrounding a magnet.

The region around a magnet where another magnet or magnetic material experiences a force.

2.

Explain why the magnetic field is strongest at the poles of a bar magnet.

Because the magnetic field lines are closest together at the poles.

3.

Describe how you could use a plotting compass to map the magnetic field around a bar magnet.

Place a plotting compass around the magnet and mark the direction of the needle at different positions to map the field lines.

4.

Explain why magnetic field lines are drawn from the north pole to the south pole of a magnet.

Because this is the direction a north pole would move in the field.

5.

Explain why the force between a magnet and a magnetic material such as iron is always attractive.

The magnetic material becomes an induced magnet with the opposite pole nearest the permanent magnet.

6.

Explain why a compass needle points towards north using the Earth's magnetic field.

The Earth acts like a giant magnet and the compass aligns with its magnetic field.

4.7.2.1 Electromagnetism

1.

Explain what happens around a conducting wire when an electric current flows through it.

A magnetic field is produced around the wire.

2.

Explain how increasing the current in a straight wire affects the strength of its magnetic field.

The magnetic field becomes stronger.

3.

Explain why winding a wire into a solenoid produces a stronger magnetic field than a straight wire.

The magnetic fields from each coil add together, producing a stronger overall field.

4.

Describe the shape of the magnetic field produced by a current-carrying solenoid.

Similar to the field around a bar magnet.

5.

Explain why placing an iron core inside a solenoid increases the strength of its magnetic field.

Iron is easily magnetised, increasing the strength of the magnetic field.

6.

Explain why an electromagnet is more useful than a permanent magnet in devices such as scrapyard cranes.

An electromagnet can be switched on and off and its strength can be changed.

4.7.2.2 Fleming's left-hand rule (HT only)

1.

Explain what happens when a current-carrying conductor is placed at right angles to a magnetic field.

A force acts on the conductor (the motor effect).

2.

State what each finger represents in Fleming's left-hand rule.

First finger = Magnetic field. Second finger = Current. Thumb = Force (motion).

3.

A conductor carrying a current of 4 A is 0.50 m long and is placed at right angles to a magnetic field of 0.30 T. Calculate the force acting on the conductor.

Force = Magnetic flux density × Current × Length = 0.30 × 4 × 0.50 = 0.6 N

4.

Explain how increasing the current through a conductor affects the force acting on it in a magnetic field.

The force increases.

5.

Explain how increasing the magnetic flux density affects the force acting on a current-carrying conductor.

The force increases.

6.

Explain why the motor effect only occurs when a conductor carries a current in a magnetic field.

Because both a magnetic field and an electric current are needed to produce the force.

4.7.2.3 Electric motors (HT only)

1.

Explain why a current-carrying coil placed in a magnetic field rotates.

Opposite sides of the coil experience forces in opposite directions, causing it to rotate.

2.

Explain how the motor effect causes an electric motor to rotate continuously.

The split-ring commutator reverses the current every half turn so the coil continues rotating in the same direction.

3.

Explain why opposite sides of the coil experience forces in opposite directions.

Because the current flows in opposite directions on each side of the coil.

4.

State the purpose of the split-ring commutator in a simple DC motor.

To reverse the current every half turn.

5.

Explain why the current in the coil must reverse every half turn in a simple DC motor.

So the turning force continues to act in the same direction.

6.

Give one everyday application of an electric motor.

Electric fan.

4.7.2.4 Loudspeakers (Physics only, HT only)

1.

Explain how a moving-coil loudspeaker converts electrical energy into sound energy.

A current-carrying coil in a magnetic field moves and causes the cone to vibrate, producing sound waves.

2.

Explain how changes in electric current cause the cone of a loudspeaker to vibrate.

The changing current changes the direction and size of the force on the coil.

3.

Explain how the motor effect is used in a pair of headphones.

The current-carrying coil moves in the magnetic field, causing vibrations that produce sound.

4.

Explain why increasing the size of the alternating current increases the movement of the loudspeaker cone.

A larger alternating current produces a larger force, so the cone moves further.

5.

Explain how pressure variations in air are produced by a loudspeaker.

The vibrating cone compresses and rarefies the surrounding air.

6.

Explain why a loudspeaker requires both a permanent magnet and a current-carrying coil.

The permanent magnet provides the magnetic field and the current-carrying coil experiences the motor effect.

4.7.3.1 Induced potential (HT only)

1.

Explain what is meant by the generator effect.

The production of a potential difference when a conductor moves through a magnetic field.

2.

Explain how moving a conductor through a magnetic field induces a potential difference.

The conductor cuts across magnetic field lines, inducing a potential difference.

3.

Explain why an induced current is only produced when the conductor forms part of a complete circuit.

Because charge can only flow if there is a complete circuit.

4.

State two factors that increase the size of the induced potential difference.

Move the conductor faster; use a stronger magnetic field.

5.

Explain how changing the direction of movement of a conductor affects the direction of the induced current.

The direction of the induced current reverses.

6.

Explain why the magnetic field produced by an induced current opposes the original change.

Because of Lenz's Law.

4.7.3.2 Uses of the generator effect (HT only)

1.

Explain how an alternator uses the generator effect to produce alternating current.

A coil rotates in a magnetic field, producing an alternating potential difference.

2.

Explain how a dynamo uses the generator effect to produce direct current.

A split-ring commutator makes the current flow in one direction.

3.

Explain the difference between the current produced by an alternator and the current produced by a dynamo.

An alternator produces alternating current; a dynamo produces direct current.

4.

Describe the shape of a graph showing the potential difference produced by an alternator against time.

A sine wave.

5.

Explain why the potential difference produced by an alternator repeatedly changes direction.

Because the direction of movement through the magnetic field reverses every half turn.

6.

Give one everyday application of the generator effect.

Bicycle dynamo.

4.7.3.3 Microphones (HT only)

1.

Explain how a moving-coil microphone converts sound waves into electrical signals.

Sound waves make a coil vibrate in a magnetic field, inducing a potential difference.

2.

Explain how pressure variations in sound waves cause the microphone coil to move.

Pressure changes from the sound wave make the diaphragm and coil vibrate.

3.

Explain how movement of the microphone coil produces a potential difference.

The moving coil cuts magnetic field lines, inducing a potential difference.

4.

Explain why the output current from a microphone changes when the sound becomes louder.

A louder sound causes larger vibrations, producing a larger induced potential difference and current.

5.

State which physical effect allows a moving-coil microphone to work.

The generator effect.

6.

Explain why microphones are described as energy transducers.

They transfer sound energy into electrical energy.

4.7.3.4 Transformers (HT only)

1.

Explain why a transformer only works with an alternating current.

Because only an alternating current produces a changing magnetic field.

2.

A transformer has 500 turns on the primary coil and 100 turns on the secondary coil. If the primary potential difference is 230 V, calculate the secondary potential difference.

Secondary potential difference = Primary potential difference × (Secondary turns ÷ Primary turns) = 230 × (100 ÷ 500) = 230 × 0.2 = 46 V

3.

Explain the difference between a step-up transformer and a step-down transformer.

A step-up transformer increases potential difference. A step-down transformer decreases potential difference.

4.

A transformer supplies 240 W to the secondary coil at a potential difference of 24 V. Calculate the current in the secondary coil.

Current = Power ÷ Potential difference = 240 ÷ 24 = 10 A

5.

Explain why electricity is transmitted across the National Grid at a high potential difference.

A higher potential difference produces a lower current for the same power, reducing energy losses due to heating.

6.

Explain how the ratio of the number of turns on the primary and secondary coils determines the potential difference across each coil.

Potential difference ratio = Number of turns ratio.

Topic 7 Review

1.

Explain the difference between a permanent magnet and an induced magnet, giving one characteristic of each.

A permanent magnet produces its own magnetic field. An induced magnet only becomes magnetic in an external magnetic field and usually loses its magnetism when the field is removed.

2.

Describe how you could use a plotting compass to investigate the magnetic field around a bar magnet.

Move a plotting compass around the magnet and mark the direction of the needle to map the magnetic field lines.

3.

A conductor carrying a current of 3 A is placed at right angles to a magnetic field of 0.40 T. If the conductor is 0.50 m long, calculate the force acting on the conductor.

Force = Magnetic flux density × Current × Length = 0.40 × 3 × 0.50 = 0.6 N

4.

Explain how the motor effect is used in both electric motors and loudspeakers.

In both devices, the motor effect causes a current-carrying conductor in a magnetic field to experience a force. In a motor this produces rotation; in a loudspeaker it causes the cone to vibrate.

5.

Explain how the generator effect is used to produce electricity in an alternator and a dynamo.

Both use the generator effect by moving a conductor through a magnetic field. An alternator produces alternating current, while a dynamo produces direct current.

6.

A transformer has 200 turns on its primary coil and 1000 turns on its secondary coil. If the primary potential difference is 12 V, calculate the secondary potential difference and state whether the transformer is a step-up or step-down transformer.

Secondary potential difference = Primary potential difference × (Secondary turns ÷ Primary turns) = 12 × (1000 ÷ 200) = 12 × 5 = 60 V. It is a step-up transformer.

4.8.1.1 The Solar System

1.

Describe the structure of the Solar System, including the Sun, planets, dwarf planets, moons and smaller bodies.

The Solar System consists of the Sun, eight planets, dwarf planets, moons, asteroids and comets orbiting the Sun.

2.

Explain why the planets orbit the Sun rather than moving away into space.

The Sun's gravitational force provides the centripetal force that keeps the planets in orbit.

3.

State the order of the eight planets from the Sun, starting with Mercury.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

4.

Explain the difference between a planet, a moon and a dwarf planet.

A planet orbits the Sun, a moon orbits a planet, and a dwarf planet orbits the Sun but has not cleared its orbit.

5.

Describe the shape of the orbit followed by a planet around the Sun.

An elliptical orbit.

6.

Explain why gravity is essential for keeping the Solar System together.

Gravity keeps the planets and other bodies in orbit around the Sun.

4.8.1.2 Life cycle of a star

1.

State the stages in the life cycle of a star from a cloud of gas and dust (nebula) to a main sequence star.

Nebula → Protostar → Main sequence star.

2.

A star is about the same size as the Sun. Describe the stages it passes through after leaving the main sequence star, ending as a black dwarf.

Main sequence star → Red giant → White dwarf → Black dwarf.

3.

A star is much bigger than the Sun. Describe its life cycle from a main sequence star to its final stage, including the supernova.

Main sequence star → Red supergiant → Supernova → Neutron star or Black hole.

4.

Explain why the life cycle of a star depends on its initial mass and compare the life cycles of a Sun-sized star and a much more massive star.

More massive stars burn their fuel faster and end in a supernova. Smaller stars become red giants and end as white dwarfs.

5.

Explain how nuclear fusion inside stars produces new elements, including why elements heavier than iron are only formed during a supernova.

Fusion joins lighter nuclei to form heavier nuclei. Elements up to iron are formed during fusion inside stars. Elements heavier than iron are formed during a supernova.

6.

Explain how the explosion of a massive star in a supernova distributes elements throughout the Universe and why this is important.

The supernova ejects elements into space, providing the material needed to form new stars and planets.

4.8.1.3 Orbital motion, natural and artificial satellites

1.

Explain the difference between a natural satellite and an artificial satellite, giving one example of each.

A natural satellite orbits naturally (e.g. the Moon). An artificial satellite is man-made (e.g. a communications satellite).

2.

Explain why the Moon remains in orbit around the Earth.

The Earth's gravity provides the centripetal force needed for its orbit.

3.

Explain why artificial satellites remain in orbit around the Earth without falling to the ground.

They move forwards while gravity continually changes their direction, keeping them in orbit.

4.

State one use of an artificial satellite in communications, weather forecasting or navigation.

GPS navigation (or weather forecasting or satellite communications).

5.

Explain why the force of gravity is needed to keep a satellite in orbit.

Gravity provides the centripetal force needed to keep the satellite moving in a circular (or nearly circular) orbit.

6.

Describe the path followed by a satellite orbiting the Earth.

A circular or elliptical orbit around the Earth.

4.8.1.4 Red-shift

1.

Explain what is meant by the red-shift of light from distant galaxies.

The increase in the wavelength of light from a galaxy moving away from the Earth.

2.

Explain how the observed red-shift provides evidence that the Universe is expanding.

It shows that galaxies are moving away from each other, so the Universe is expanding.

3.

Explain why galaxies that are further away generally have a greater red-shift.

Because they are moving away faster.

4.

Describe what happens to the wavelength of light when a galaxy is moving away from the Earth.

The wavelength increases (it shifts towards the red end of the spectrum).

5.

Explain what the Big Bang theory suggests about the origin of the Universe.

The Universe began from an extremely hot, dense state and has been expanding ever since.

6.

Explain how observations of distant galaxies support the Big Bang theory.

Nearly all distant galaxies show red-shift, supporting the idea that the Universe is expanding from a common origin.

Topic 8 Review

1.

Explain how gravity keeps the planets in orbit around the Sun.

The Sun's gravitational force provides the centripetal force that keeps the planets in orbit.

2.

Compare the life cycle of a star about the same size as the Sun with the life cycle of a star much bigger than the Sun.

A Sun-sized star becomes a red giant, then a white dwarf, and finally a black dwarf. A much larger star becomes a red supergiant, explodes as a supernova, and ends as either a neutron star or a black hole.

3.

Explain how nuclear fusion in stars produces new elements and why elements heavier than iron are formed during a supernova.

Nuclear fusion joins lighter nuclei to form heavier nuclei. Elements heavier than iron are produced during the enormous energy release of a supernova.

4.

Explain the difference between a natural satellite and an artificial satellite, giving one example of each.

A natural satellite orbits naturally (e.g. the Moon). An artificial satellite is man-made (e.g. a communications satellite).

5.

Explain what is meant by the red-shift of light from distant galaxies and what it tells scientists about the Universe.

Red-shift is the increase in the wavelength of light from distant galaxies. It shows that the Universe is expanding.

6.

A star is observed as a main sequence star. Explain the possible stages that could follow if the star is about the same size as the Sun and if it is much bigger than the Sun.

If it is about the same size as the Sun: Red giant → White dwarf → Black dwarf. If it is much larger than the Sun: Red supergiant → Supernova → Neutron star or Black hole.

Physics

Paper 1

Topic 1 – Energy

4.1.1.1 Energy stores and systems

4.1.1.2 Changes in energy

4.1.1.3 Energy changes in systems

4.1.1.4 Power

4.1.2.1 Energy transfers in a system

4.1.2.2 Efficiency

4.1.3 National and global energy resources

Topic 1 Review

Topic 2 – Electricity

4.2.1.1 Standard circuit diagram symbols

4.2.1.2 Electrical charge and current

4.2.1.3 Current, resistance and potential difference

4.2.2 Series and parallel circuits

4.2.3.1 Direct and alternating potential difference

4.2.3.2 Mains electricity

4.2.4.1 Power

4.2.4.2 Energy transfers in everyday appliances

4.2.4.3 The National Grid

4.2.5.1 Static charge (Physics only)

4.2.5.2 Electric fields (Physics only)

Topic 2 Review

Topic 3 – Particle Model of Matter

4.3.1.1 Density of materials

4.3.1.2 Changes of state

4.3.2.1 Internal energy

4.3.2.2 Temperature changes in a system and specific heat capacity

4.3.2.3 Changes of state and specific latent heat

4.3.3.1 Particle motion in gases

4.3.3.2 Pressure in gases

4.3.3.3 Increasing the pressure of a gas (HT only)

Topic 3 Review

Topic 4 – Atomic Structure

4.4.1.1 The structure of an atom

4.4.1.2 Mass number, atomic number and isotopes

4.4.1.3 The development of the model of the atom

4.4.2.1 Radioactive decay and nuclear radiation

4.4.2.2 Nuclear equations

4.4.2.3 Half-lives and the random nature of radioactive decay

4.4.2.4 Radioactive contamination

4.4.3.1 Background radiation

4.4.3.2 Different half-lives of radioactive isotopes

4.4.3.3 Uses of nuclear radiation

4.4.4.1 Nuclear fission

4.4.4.2 Nuclear fusion

Topic 4 Review

Paper 2

Topic 5 – Forces

4.5.1.1 Scalar and vector quantities

4.5.1.2 Contact and non-contact forces

4.5.1.3 Gravity

4.5.1.4 Resultant forces

4.5.2 Work done and energy transfer

4.5.3 Forces and elasticity

4.5.4 Moments, levers and gears

4.5.5.1 Pressure in a fluid 1

4.5.5.1.2 Pressure in a fluid 2 (HT)

4.5.5.2 Atmospheric pressure

4.5.6.1.1 Distance and displacement

4.5.6.1.2 Speed

4.5.6.1.3 Velocity

4.5.6.1.4 Distance-time relationship

4.5.6.1.5 Acceleration

4.5.6.2.1 Newton’s First Law

4.5.6.2.2 Newton’s Second Law

4.5.6.2.3 Newton’s Third Law

4.5.6.3.1 Stopping distance

4.5.6.3.2 Reaction time

4.5.6.3.3 Factors affecting braking distance 1

4.5.6.3.4 Factors affecting braking distance 2

4.5.7.1 Momentum is a property of moving objects (HT)

4.5.7.2 Conservation of momentum (HT)

4.5.7.3 Changes in momentum (HT)

Topic 5 Review

Topic 6 – Waves

4.6.1.1 Transverse and longitudinal waves

4.6.1.2 Properties of waves

4.6.1.3 Reflection of waves (Physics only)