Science 7 · Unit 3: Forces and energy · Cambridge Lower Secondary Science Stage 7

Questions

1. 1. Energy must be ... to make something happen.

   • destroyed
   • wasted
   • transferred
   • stored
   Check

2. 2. Energy that can be kept for a long time is ... energy.

   • dissipated
   • wasted
   • useful
   • stored
   Check

3. 3. Energy that we want is called ... energy.

   • useful
   • wasted
   • stored
   • dissipated
   Check

4. 4. Energy that we do not want is called ... energy.

   • useful
   • wasted
   • stored
   • transferred
   Check

5. 5. Energy that is wasted cannot be ...

   • measured
   • dissipated
   • recovered
   • transferred
   Check

6. 6. Energy that spreads out and becomes less useful has been ...

   • dissipated
   • destroyed
   • stored
   • recovered
   Check

7. 7. Which three forms of energy spread out and cannot be used again?

   • kinetic, gravitational potential and elastic
   • chemical, elastic and kinetic
   • electrical, chemical and light
   • light, thermal and sound
   Check

8. 8. Although energy can be wasted, it can never be ...

   • destroyed
   • transferred
   • stored
   • dissipated
   Check

9. 9. Zara's three beakers start at different temperatures. Which variable must she keep constant?

   • the volume of water in each beaker
   • the starting temperature of the water
   • the temperature after 10 minutes
   • the time she started each beaker
   Check

10. 10. Which other variable should Zara keep constant?

    • the type and size of the beakers
    • the colour of the thermometer
    • the starting temperature
    • the final temperature
    Check

11. 11. The water in each beaker cools down. Which energy is lost from the water?

    • chemical
    • kinetic
    • thermal
    • elastic
    Check

12. 12. Where does the thermal energy from the cooling water go?

    • to the surrounding air and the beaker
    • into the thermometer only
    • into chemical energy in the water
    • It is destroyed.
    Check

13. 13. Zara thinks the thermal energy from her hot water goes into the air. How could she show this?

    • Look at the colour of the water.
    • Weigh the beaker before and after.
    • Measure the volume of the water.
    • Measure the temperature of the air close to the beaker, and see if it rises.
    Check

14. 14. Which extra safety precaution does Zara need in this investigation?

    • Wear gloves to touch electric wires.
    • Take care not to spill or touch the hot water.
    • Keep the windows closed.
    • Use a magnet.
    Check

15. 15. A machine transfers some of the energy it uses to wasted energy. How do you calculate the percentage of useful energy?

    • the percentage of wasted energy plus 100%
    • 100% minus the percentage of wasted energy
    • the percentage of wasted energy divided by 2
    • the same as the percentage of wasted energy
    Check

16. 16. A petrol engine in a car transfers some of the energy it uses to useful energy. How do you calculate the percentage that is wasted?

    • the percentage of useful energy times 2
    • the same as the percentage of useful energy
    • 100% minus the percentage of useful energy
    • the percentage of useful energy plus 100%
    Check

17. 17. How is energy wasted by a car engine?

    • as thermal energy and sound
    • as kinetic energy of the car
    • as chemical energy in the petrol
    • It is destroyed.
    Check

18. 18. A diesel engine transfers more of its energy to useful energy than a petrol engine, but it is more expensive. Why do large trucks use diesel engines?

    • Trucks travel long distances, so saving fuel saves more money than the engine costs.
    • Diesel engines are lighter.
    • Diesel engines waste more energy.
    • Trucks only travel short distances.
    Check