Year 7 Energy Worksheet - Intermediate

Year 7 Energy worksheet for Year 7 (Key Stage 3 / Year 7-9 (Ages 11-14)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Energyintermediate

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Year 7 Energy: Stores, Transfers and Resources

Key Stage 3 Science | Ages 11–12 | Intermediate

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Instructions: Complete the activities in order, showing your working for calculations. Use the information printed in each question; energy is measured in joules (J), power in watts (W), and time in seconds (s) unless stated otherwise.

Energy Stores and Transfers

For each situation, identify the main energy store that decreases and the useful store that increases. Name the transfer pathway where asked. Some energy may also be dissipated to the surroundings as thermal energy.

1. A battery-powered torch is switched on. Which energy store decreases in the battery, and which useful energy store increases in the light produced?

2. A cyclist brakes to stop. Which energy store decreases, and which energy store increases in the brakes and surroundings?

3. A ball is held above the ground and then released. As it falls, which energy store decreases and which increases?

4. An electric kettle warms water. Name the energy transfer pathway from the mains supply to the water.

Conservation of Energy

Use the idea that energy is transferred between stores, not created or destroyed. In each answer, account for the energy supplied, the useful energy and any energy dissipated to the surroundings.

1. A motor receives 100 J of energy. It transfers 70 J usefully to a moving object. How much energy is dissipated to the surroundings?

2. A lamp receives 60 J of electrical energy and transfers 8 J as light. How much is transferred to the surroundings by other pathways?

3. A toy car starts with 45 J in its kinetic store. It stops, and 45 J is transferred to the surroundings. State whether energy has been conserved and explain briefly.

4. A student says, “The energy disappeared when the ball stopped.” Explain why this statement is incorrect.

Renewable and Non-renewable Resources

Classify each resource as renewable or non-renewable. Then consider how its use affects reliable electricity generation. Use complete answers for the final question.

1. Is wind energy renewable or non-renewable?

2. Is natural gas renewable or non-renewable?

3. Is energy from sunlight renewable or non-renewable?

4. Is energy from uranium in a nuclear power station renewable or non-renewable?

5. Give one advantage and one limitation of using wind power to generate electricity.

Power Ratings and Appliance Costs

Use energy transferred = power × time. For cost calculations, convert watts to kilowatts by dividing by 1,000, then use: cost = energy used in kWh × price per kWh. The electricity price is 30 p per kWh.

1. A 1,000 W kettle runs for 3 minutes. Calculate the energy transferred in joules.

2. A 2,000 W heater runs for 2 hours. Calculate the energy used in kWh.

3. Using the price given above, calculate the cost of running the heater in Question 2. Give your answer in pence.

4. A 100 W lamp is used for 5 hours. Calculate the energy used in kWh.

Heating and Thermal Energy Transfer

Choose the correct thermal transfer process: conduction, convection or radiation. For the final question, explain how the material or motion of particles helps the transfer happen.

1. A metal spoon becomes warm while resting in hot tea. Name the main transfer process along the spoon.

2. Warm air rises above a radiator and cooler air moves in to replace it. Name the transfer process in the moving air.

3. Energy from the Sun travels through space to warm Earth. Name the transfer process.

4. Explain why a metal saucepan handle may become hot when the pan is heated on a hob.

Putting Energy Ideas Together

Read the situation carefully and use energy-store and transfer vocabulary. Show a calculation where needed, and include the unit in your answer.

A 40 W lamp is switched on for 30 minutes. It transfers 24,000 J usefully as light; the rest is transferred to the surroundings as thermal energy.

1. Calculate the total energy transferred by the lamp in 30 minutes.

2. Calculate the energy transferred to the surroundings as thermal energy.

3. Name the energy store of the lamp’s electrical supply before the lamp is switched on.

4. Explain how this example demonstrates conservation of energy.

Answer Key

Activity 1: 1. Chemical store decreases; light energy store increases. 2. Kinetic store decreases; thermal energy store of the brakes and surroundings increases. 3. Gravitational potential store decreases; kinetic store increases. 4. Electrically, then by heating to the water (electrical transfer followed by heating).

Activity 2: 1. 30 J. 2. 52 J. 3. Yes; the 45 J is transferred to the surroundings, so the total energy is conserved. 4. Energy is transferred to the surroundings, mainly by heating and sound; it is not destroyed.

Activity 3: 1. Renewable. 2. Non-renewable. 3. Renewable. 4. Non-renewable. 5. Advantage: it generates electricity without burning fuel and has low operational greenhouse-gas emissions. Limitation: output depends on wind, so it is variable.

Activity 4: 1. 180,000 J (1,000 × 180). 2. 4 kWh (2 kW × 2 h). 3. 120 p (4 × 30 p). 4. 0.5 kWh (0.1 kW × 5 h).

Activity 5: 1. Conduction. 2. Convection. 3. Radiation. 4. Thermal energy is transferred through the metal by conduction as particles transfer energy along the handle.

Activity 6: 1. 72,000 J (40 × 1,800). 2. 48,000 J (72,000 − 24,000). 3. The electrical store of the supply (or the chemical store of the power station’s fuel, where applicable). 4. The total 72,000 J is accounted for as 24,000 J transferred as light and 48,000 J transferred to the surroundings as thermal energy; energy is transferred, not created or destroyed.