Energy Calculations Worksheet - GCSE - Intermediate

Energy Calculations worksheet for GCSE (Key Stage 4 / GCSE (Ages 14-16)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 4 / GCSE (Ages 14-16)•Energy Calculationsintermediate

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GCSE Physics: Energy Calculations

Key Stage 4 (ages 14–16) • Intermediate • AQA-style

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Instructions: Use the equations provided and show your working, including units. Give answers to an appropriate number of significant figures. Unless stated otherwise, use g = 9.8 N/kg.

Kinetic energy

Use Ek = ½mv². Substitute the values, show your working and include the correct unit for energy.

1. A 1,200 kg car travels at 15 m/s. Calculate its kinetic energy.

2. A 0.50 kg ball moves at 8.0 m/s. Calculate its kinetic energy.

3. A 900 kg car has 72,000 J of kinetic energy. Calculate its speed.

4. A cyclist and bicycle have a combined mass of 80 kg and travel at 5.0 m/s. Calculate their kinetic energy.

Gravitational potential energy

Use Ep = mgh. Show the substitution and calculation, and state your answer in joules.

1. A 5.0 kg object is lifted vertically by 3.0 m. Calculate the increase in gravitational potential energy.

2. A 60 kg climber rises 12 m. Calculate the increase in gravitational potential energy.

3. A 2.0 kg book gains 49 J of gravitational potential energy when lifted. Calculate the vertical height through which it is lifted.

4. A 1,500 kg lift rises 8.0 m. Calculate its gain in gravitational potential energy.

Power and energy transfer

Use P = E/t or P = W/t as appropriate. Rearrange the equation when needed, and include units in each answer.

1. A motor transfers 18,000 J of energy in 30 s. Calculate its power.

2. A 2.0 kW kettle operates for 150 s. Calculate the energy it transfers in joules.

3. A machine does 24,000 J of work at a power of 800 W. Calculate the time taken.

4. A crane lifts a load, doing 36,000 J of work in 45 s. Calculate the crane's power.

Efficiency

Use efficiency = useful energy output ÷ total energy input. Convert your answer to a percentage where requested. Identify the useful output before calculating.

1. A motor receives 500 J of energy and transfers 350 J usefully. Calculate its efficiency as a percentage.

2. A lamp transfers 120 J usefully as light from 600 J of electrical energy. Calculate its efficiency as a percentage.

3. A machine is 80% efficient and receives 2,500 J of energy. Calculate its useful energy output.

4. A device transfers 900 J usefully from a total input of 1,200 J. Calculate the energy dissipated and the efficiency as a percentage.

Specific heat capacity

Use Q = mcΔT, where Q is energy transferred, m is mass, c is specific heat capacity and ΔT is temperature change. Show your working and include units.

1. A 2.0 kg aluminium block (c = 900 J/kg°C) is heated from 20°C to 50°C. Calculate the energy transferred to it.

2. A 0.50 kg sample of water (c = 4,200 J/kg°C) receives 8,400 J of energy. Calculate its temperature change.

3. A 1.5 kg substance receives 18,000 J as its temperature rises by 20°C. Calculate its specific heat capacity.

4. A 0.80 kg iron block (c = 450 J/kg°C) cools from 100°C to 40°C. Calculate the energy transferred from the block.

Choose and apply the equation

Select the relevant equation for each problem from Ek = ½mv², Ep = mgh, P = E/t, efficiency = useful output ÷ total input, or Q = mcΔT. Show the equation you chose, substitute values and give a correctly unit-labelled answer.

1. A 4.0 kg object is moving at 6.0 m/s. Calculate its kinetic energy.

2. A 10 kg box is raised 2.5 m. Calculate its gain in gravitational potential energy.

3. A heater transfers 90,000 J in 60 s. Calculate its power.

4. A 0.25 kg copper sample (c = 390 J/kg°C) is heated by 40°C. Calculate the energy transferred.

Answer Key

Activity 1: 1. 135,000 J ; 2. 16 J ; 3. 12.6 m/s (approximately) ; 4. 1,000 J

Activity 2: 1. 147 J ; 2. 7,056 J ; 3. 2.5 m ; 4. 117,600 J

Activity 3: 1. 600 W ; 2. 300,000 J ; 3. 30 s ; 4. 800 W

Activity 4: 1. 70% ; 2. 20% ; 3. 2,000 J ; 4. 300 J dissipated and 75%

Activity 5: 1. 54,000 J ; 2. 4°C ; 3. 600 J/kg°C ; 4. 21,600 J transferred from the block

Activity 6: 1. 72 J ; 2. 245 J ; 3. 1,500 W ; 4. 3,900 J