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9th grade energy

9th grade (Year 10 in England) · 16 questions · Common Core: NGSS.MS-PS3-1, NGSS.MS-PS3-2, NGSS.HS-PS3-1, NGSS.HS-PS3-2 · England: KS4 Combined Science: Energy, KS3 Physics: Energy (calculation of fuel uses and costs), GCSE Combined Science: Energy (national and global energy resources)

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  1. Question 1

    A ball is dropped from 5 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg.

    Answerm/s

  2. Question 2

    An appliance transfers 50 J of energy in 10 s. What is its power, in watts?

    AnswerW

  3. Question 3

    An object of mass 50 kg is lifted 25 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg.

    AnswerJ

  4. Question 4

    A 3 kW heater is used for 4 hours. Electricity costs 15 cents (pence) per kWh. How much does it cost to run, in cents (pence)?

    Answer

  5. Question 5

    A device is supplied with 2500 J and transfers 250 J usefully. What is its efficiency, as a percentage?

    Answer%

  6. Question 6

    Can a device be more than 100% efficient?

    • A. No, because energy cannot be created
    • B. Yes, if it uses a battery
    • C. Yes, if it is very small
    • D. Yes, if it is new

  7. Question 7

    What is the kinetic energy of a 80 kg object moving at 20 m/s? Use Eₖ = ½ m v².

    AnswerJ

  8. Question 8

    Why are large batteries and pumped hydro storage being built alongside renewables?

    • A. To store surplus energy and release it when demand is high or generation is low
    • B. Because renewables need batteries to start
    • C. To make renewables produce more carbon dioxide
    • D. To replace transmission lines

  9. Question 9

    A motor is 20% efficient. It is supplied with 2000 J. How much useful energy does it transfer, in J?

    AnswerJ

  10. Question 10

    Is this energy resource renewable or non-renewable: coal?

    • A. renewable
    • B. non-renewable

  11. Question 11

    A force of 150 N pushes a box 2 m along the floor. How much work is done, in J?

    AnswerJ

  12. Question 12

    In one year a country generated 200 TWh of electricity. Renewables supplied (TWh): wind 46, solar 28, hydroelectric 16. What percentage of the electricity came from these renewables?

    Answer%

  13. Question 13

    A ball is dropped from 45 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg.

    Answerm/s

  14. Question 14

    An appliance transfers 20 J of energy in 2 s. What is its power, in watts?

    AnswerW

  15. Question 15

    An object of mass 60 kg is lifted 25 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg.

    AnswerJ

  16. Question 16

    A 3 kW heater is used for 5 hours. Electricity costs 30 cents (pence) per kWh. How much does it cost to run, in cents (pence)?

    Answer

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  1. 10 m/s
  2. 5 W
  3. 12250 J
  4. 180
  5. 10 %
  6. No, because energy cannot be created
  7. 16000 J
  8. To store surplus energy and release it when demand is high or generation is low
  9. 400 J
  10. non-renewable
  11. 300 J
  12. 45 %
  13. 30 m/s
  14. 10 W
  15. 14700 J
  16. 450