Lesson T1.3.1

T1.3.1 Conservation of energy Quiz: KS3 Physics, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T1.3.1, Conservation of energy: 20 multiple choice questions for the KS3 Physics (National Curriculum), Unit 1: Energy, written with Revision Ninja.

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The 20 questions

  1. What does it mean to say that energy is conserved?

    • Energy is always gained during a change, so the total rises over time
    • The total energy before a change equals the total energy after it
    • Energy only increases in closed systems, where none can leave the system
    • Energy is always used up during a change, so the total falls after every change

  2. A closed system holds 800 J of energy. After a change, 600 J is in useful stores. How much energy is in the thermal stores of the surroundings?

    • 1400 J
    • 200 J
    • 0 J
    • 600 J

  3. What is meant by the dissipation of energy?

    • Energy being converted into mass, so the object gains weight as it changes
    • Energy being destroyed completely, so none of it is left in any store afterwards
    • Energy spreading out into the surroundings, usually as thermal energy, so it is less useful
    • Energy being collected into a single store, where it can be used again later

  4. A roller coaster has 50 000 J of gravitational potential energy at the top. Ignoring losses, what is its kinetic energy at the bottom?

    • 100 000 J
    • 0 J
    • 25 000 J
    • 50 000 J

  5. A pendulum swings for a while before stopping. Why does it eventually stop?

    • Energy is destroyed by gravity, which pulls the pendulum down to rest completely
    • Gravity stops working near the pendulum, so the swing has no force left in it
    • Energy is dissipated to thermal stores by air resistance and friction at the pivot
    • The pendulum gains mass as it swings, which makes it heavier and slows it down

  6. In a closed system, which quantity stays constant during a change?

    • Total energy
    • Energy in useful stores
    • Thermal energy
    • Kinetic energy

  7. A system receives 400 J of input energy and gives 250 J of useful output. How much energy is dissipated?

    • 150 J
    • 400 J
    • 250 J
    • 650 J

  8. A lamp receives 100 J of electrical energy each second. 10 J becomes light and 90 J becomes thermal energy. Which statement is correct?

    • The output is 10 J and the rest is lost forever
    • The output is 110 J, more than the input
    • The total output is 100 J, equal to the input
    • The thermal energy is destroyed

  9. Why does a hot cup of coffee not reheat itself?

    • Its energy has spread out to the surroundings, so it cannot regain it by itself
    • Coffee cannot store thermal energy, so it has no way of holding onto heat
    • The cup absorbs cold from the room, so it stays cool and cannot reheat
    • The coffee loses all its mass as it cools, so there is nothing left to reheat

  10. Why is it hard to recover energy once it has been dissipated?

    • It is spread out among many particles, making it hard to collect
    • It has been converted entirely into sound, which quickly fades away
    • It has been destroyed by the process, so it cannot be recovered at all
    • It has been converted into mass, which is held inside the materials

  11. A car engine burns fuel with 1000 kJ of chemical energy. 300 kJ becomes the kinetic energy of the car. What happens to the rest?

    • Destroyed by the engine's combustion, so it does not appear in any store
    • Mainly transferred to thermal energy of the engine and surroundings
    • Stored permanently as gravitational potential energy in the raised car
    • Stored as extra mass in the car, which makes the car heavier as it runs

  12. A system starts with 5000 J of energy. It ends with 3000 J in kinetic stores and 2000 J in thermal stores. Is energy conserved?

    • Yes, the total is still 5000 J
    • No, 2000 J has been destroyed
    • No, energy has been created
    • No, 3000 J has disappeared into mass

  13. A bulb uses 60 J of electrical energy each second and gives out 6 J of light. What happens to the rest?

    • 60 J is stored in the filament forever
    • 6 J is destroyed
    • 54 J is transferred to thermal energy
    • 66 J is created

  14. A falling object loses gravitational potential energy. Which statement describes this correctly?

    • Both stores decrease together
    • Both the gravitational and kinetic stores increase
    • The kinetic store decreases while the gravitational store increases
    • The decrease in gravitational potential store matches the increase in kinetic store

  15. Which change is an example of dissipation?

    • A spring being stretched in a lab
    • A ball rolling up a slope
    • A battery powering a motor
    • Hot water cooling down in a room

  16. A 1 kg mass gains 50 J of kinetic energy and loses 80 J of gravitational potential energy. How much energy is dissipated?

    • 130 J
    • 50 J
    • 30 J
    • 80 J

  17. A system has 2500 J of energy. 2000 J ends up in useful stores. What percentage is useful?

    • 80%
    • 20%
    • 125%
    • 50%

  18. A wind turbine converts 1000 J of kinetic energy and produces 700 J of electrical energy. What is its efficiency?

    • 700%
    • 70%
    • 1000%
    • 30%

  19. A swing has 300 J of gravitational potential energy at its highest point. Ignoring losses, what is its kinetic energy at the lowest point?

    • 150 J
    • 600 J
    • 0 J
    • 300 J

  20. Which change involves a moving ball being brought to a stop by compressing a spring?

    • Thermal energy is converted into chemical energy
    • Gravitational potential energy is converted into thermal energy
    • Elastic potential energy is converted into kinetic energy
    • Kinetic energy is converted into elastic potential energy

All KS3 Physics quizzes