Energy
50 exam-style questions with answers for 4.1 Energy in AQA GCSE Physics (spec 8463). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official AQA material.
All 50 questions and answers
Question 1 · Spec 4.1.1.1 · Energy stores
Name four energy stores. [4 marks]
Answer:Any four from: kinetic (1); gravitational potential (1); elastic potential (1); thermal (1); chemical (1); magnetic (1); electrostatic (1); nuclear (1).Question 2 · Spec 4.1.1.1 · Energy stores
Describe the energy changes when a ball is thrown upwards. [2 marks]
Answer:The ball's kinetic energy store decreases as it rises (1); its gravitational potential energy store increases (1).Question 3 · Spec 4.1.1.1 · Energy stores
Describe the energy changes when a car brakes. [2 marks]
Answer:The kinetic energy store of the car decreases (1); work done by friction increases the thermal energy store of the brakes (1).Question 4 · Spec 4.1.1.2 · Kinetic energy
State the equation for kinetic energy. [1 mark]
Answer:Kinetic energy = 0.5 × mass × speed² (Eₖ = ½mv²).Question 5 · Spec 4.1.1.2 · Kinetic energy
Calculate the kinetic energy of a 60 kg runner moving at 5 m/s. [2 marks]
Answer:Eₖ = 0.5 × 60 × 5² (1); = 750 J (1).Question 6 · Spec 4.1.1.2 · Gravitational potential energy
Calculate the gain in GPE when a 2 kg book is lifted 1.5 m. Use g = 9.8 N/kg. [2 marks]
Answer:Eₚ = mgh = 2 × 9.8 × 1.5 (1); = 29.4 J (1).Question 7 · Spec 4.1.1.2 · Elastic potential energy
Calculate the elastic potential energy in a spring with k = 200 N/m stretched by 0.1 m. [2 marks]
Answer:Eₑ = 0.5 × k × e² = 0.5 × 200 × 0.1² (1); = 1 J (1).Question 8 · Spec 4.1.1.2 · Kinetic energy
A 0.5 kg ball falls from 5 m. Calculate its speed just before landing, ignoring air resistance. Use g = 9.8 N/kg. [3 marks]
Answer:GPE lost = 0.5 × 9.8 × 5 = 24.5 J (1); 24.5 = 0.5 × 0.5 × v², so v² = 98 (1); v = 9.9 m/s (1).Question 9 · Spec 4.1.1.3 · Specific heat capacity
Define specific heat capacity. [1 mark]
Answer:The amount of energy needed to raise the temperature of 1 kg of a substance by 1 °C.Question 10 · Spec 4.1.1.3 · Specific heat capacity
Calculate the energy needed to heat 2 kg of water from 20 °C to 70 °C. Specific heat capacity of water = 4200 J/kg °C. [2 marks]
Answer:ΔE = mcΔθ = 2 × 4200 × 50 (1); = 420 000 J (1).Question 11 · Spec 4.1.1.3 · Required practical 1
Describe how to measure the specific heat capacity of a metal block. [3 marks]
Answer:Measure the mass of the block and insert a heater and thermometer (1); record the energy supplied with a joulemeter (or from power × time) and the temperature rise (1); calculate c = ΔE ÷ (mΔθ) (1).Question 12 · Spec 4.1.1.3 · Required practical 1
Why is the block wrapped in insulation? [1 mark]
Answer:To reduce energy lost to the surroundings, so the value of c is more accurate.Question 13 · Spec 4.1.1.3 · Required practical 1
Why is the measured specific heat capacity usually higher than the true value? [1 mark]
Answer:Some energy is lost to the surroundings, so more energy is supplied than goes into the block.Question 14 · Spec 4.1.1.4 · Power
Define power. [1 mark]
Answer:The rate at which energy is transferred or the rate at which work is done.Question 15 · Spec 4.1.1.4 · Power
State the unit of power and what it means. [2 marks]
Answer:The watt (W) (1); 1 W is an energy transfer of 1 joule per second (1).Question 16 · Spec 4.1.1.4 · Power
A motor transfers 3000 J in 20 s. Calculate its power. [2 marks]
Answer:P = E ÷ t = 3000 ÷ 20 (1); = 150 W (1).Question 17 · Spec 4.1.1.4 · Power
Two motors lift the same load to the same height. One takes 4 s and the other 8 s. Which is more powerful? [1 mark]
Answer:The one taking 4 s, as it transfers the same energy in less time.Question 18 · Spec 4.1.2.1 · Conservation of energy
State the principle of conservation of energy. [1 mark]
Answer:Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.Question 19 · Spec 4.1.2.1 · Dissipation
What is meant by 'wasted' energy? [1 mark]
Answer:Energy that is dissipated, usually to the surroundings as thermal energy, and is not useful.Question 20 · Spec 4.1.2.1 · Reducing waste
State two ways to reduce unwanted energy transfers. [2 marks]
Answer:Any two from: lubrication to reduce friction (1); thermal insulation (1); streamlining (1).Question 21 · Spec 4.1.2.1 · Thermal conductivity
How does the thickness and thermal conductivity of a building's walls affect energy loss? [2 marks]
Answer:Thicker walls reduce the rate of energy transfer (1); walls with lower thermal conductivity reduce the rate of energy transfer (1).Question 22 · Spec 4.1.2.1 · Required practical 2
Describe how to compare the effectiveness of insulating materials. [3 marks]
Answer:Wrap beakers of hot water in different materials of the same thickness (1); measure the starting temperature and the temperature after a set time (1); the material with the smallest temperature drop is the best insulator (1).Question 23 · Spec 4.1.2.2 · Efficiency
State the equation for efficiency. [1 mark]
Answer:Efficiency = useful energy output ÷ total energy input (or useful power output ÷ total power input).Question 24 · Spec 4.1.2.2 · Efficiency
A lamp uses 200 J and gives out 30 J of light. Calculate its efficiency. [2 marks]
Answer:30 ÷ 200 (1); = 0.15 (15%) (1).Question 25 · Spec 4.1.2.2 · Efficiency
A motor is 40% efficient. It has an input power of 500 W. Calculate the useful output power. [2 marks]
Answer:Useful power = 0.40 × 500 (1); = 200 W (1).Question 26 · Spec 4.1.2.2 · Efficiency · Higher only
State two ways to increase the efficiency of a machine. [2 marks]
Answer:Any two from: lubricate moving parts to reduce friction (1); insulate to reduce thermal losses (1); reduce electrical resistance in wires (1).Question 27 · Spec 4.1.3 · Energy resources
Name three non-renewable energy resources. [3 marks]
Answer:Coal and oil (1); natural gas (1); nuclear fuel (1).Question 28 · Spec 4.1.3 · Energy resources
What is a renewable energy resource? [1 mark]
Answer:One that is being, or can be, replenished as it is used.Question 29 · Spec 4.1.3 · Energy resources
Name four renewable energy resources. [4 marks]
Answer:Any four from: bio-fuel (1); wind (1); hydro-electricity (1); geothermal (1); tides (1); the Sun (solar) (1); water waves (1).Question 30 · Spec 4.1.3 · Energy resources
State the main uses of energy resources. [3 marks]
Answer:Transport (1); electricity generation (1); heating (1).Question 31 · Spec 4.1.3 · Fossil fuels
State one advantage and one disadvantage of using coal. [2 marks]
Answer:Advantage: reliable and can be used to generate large amounts of electricity at any time (1). Disadvantage: releases carbon dioxide, causing global warming, and sulfur dioxide, causing acid rain (1).Question 32 · Spec 4.1.3 · Wind
State one advantage and one disadvantage of wind turbines. [2 marks]
Answer:Advantage: no fuel costs and no carbon dioxide produced while running (1). Disadvantage: unreliable, as no electricity is generated when the wind does not blow (1).Question 33 · Spec 4.1.3 · Solar
Why are solar cells not suitable for supplying all of the UK's electricity? [2 marks]
Answer:They do not generate electricity at night (1); and generate little in cloudy weather (1).Question 34 · Spec 4.1.3 · Nuclear
State one advantage and one disadvantage of nuclear power. [2 marks]
Answer:Advantage: no carbon dioxide released and very reliable (1). Disadvantage: produces radioactive waste that must be stored safely for a long time (1).Question 35 · Spec 4.1.3 · Hydro-electricity
State one disadvantage of hydro-electric power. [1 mark]
Answer:Building a dam floods valleys, destroying habitats and possibly homes.Question 36 · Spec 4.1.3 · Tidal
Why is tidal power more reliable than wave power? [1 mark]
Answer:Tides are predictable and happen twice a day, while waves depend on the weather.Question 37 · Spec 4.1.3 · Geothermal
Why is geothermal energy only used in some places? [1 mark]
Answer:It needs hot rocks close to the surface, found mainly in volcanic areas.Question 38 · Spec 4.1.3 · Bio-fuel
Why are bio-fuels described as carbon neutral? [2 marks]
Answer:The plants absorb carbon dioxide as they grow (1); the same amount is released when the fuel is burned (1).Question 39 · Spec 4.1.3 · Energy resources
Why is the use of renewable resources increasing? [2 marks]
Answer:Fossil fuels will run out (1); and concern about the environmental effects of burning them, such as global warming (1).Question 40 · Spec 4.1.3 · Energy resources
State one reason why the UK still uses fossil fuels. [1 mark]
Answer:They are reliable and can meet sudden increases in demand, while renewables can be unreliable.Question 41 · Spec 4.1.1.2 · Gravitational potential energy
State the equation for gravitational potential energy. [1 mark]
Answer:GPE = mass × gravitational field strength × height (Eₚ = mgh).Question 42 · Spec 4.1.1.3 · Specific heat capacity
8400 J heats 0.5 kg of oil by 8 °C. Calculate the specific heat capacity of the oil. [2 marks]
Answer:c = ΔE ÷ (mΔθ) = 8400 ÷ (0.5 × 8) (1); = 2100 J/kg °C (1).Question 43 · Spec 4.1.1.4 · Power
A kettle has a power of 2000 W. How much energy does it transfer in 3 minutes? [2 marks]
Answer:E = P × t = 2000 × 180 (1); = 360 000 J (1).Question 44 · Spec 4.1.1.4 · Work done
A force of 50 N moves an object 4 m. Calculate the work done. [2 marks]
Answer:W = F × s = 50 × 4 (1); = 200 J (1).Question 45 · Spec 4.1.1.1 · Systems
What is meant by a 'closed system'? [1 mark]
Answer:A system where no energy enters or leaves, so the total energy does not change.Question 46 · Spec 4.1.2.2 · Efficiency
Why can no device be 100% efficient? [1 mark]
Answer:Some energy is always dissipated to the surroundings, usually as thermal energy.Question 47 · Spec 4.1.1.2 · Kinetic energy
A car doubles its speed. What happens to its kinetic energy? [1 mark]
Answer:It increases four times, because kinetic energy depends on speed squared.Question 48 · Spec 4.1.2.1 · Thermal conductivity
Why do houses have cavity wall insulation? [2 marks]
Answer:The insulation traps air, which has low thermal conductivity (1); this reduces the rate of energy transfer out of the house (1).Question 49 · Spec 4.1.3 · Energy resources
Describe the trend in UK electricity generation from coal since 2010. [1 mark]
Answer:It has fallen sharply as coal power stations have closed and renewables have increased.Question 50 · Spec 4.1.3 · Environmental issues
State two environmental problems caused by burning fossil fuels. [2 marks]
Answer:Any two from: carbon dioxide causes global warming (1); sulfur dioxide causes acid rain (1); particulates cause global dimming and breathing problems (1).