Chapter 1 Practice Paper: Energy stores and conservation — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   A stretched diving board stores energy mainly in its

   1. Akinetic store
   2. Belastic store
   3. Cnuclear store
   4. Dmagnetic store
   ( )
2. 2

   Energy moves from a hot drink to the cool air around it by

   1. Aheating
   2. Belectrical working
   3. Cnuclear decay
   4. Dchemical reaction
   ( )
3. 3

   In a closed system, the total energy of all the stores

   1. Aslowly runs out
   2. Bincreases
   3. Cstays constant
   4. Ddecreases by friction each second
   ( )
4. 4

   A machine is 60% efficient. Of every 200 J supplied, the useful output is

   1. A60 J
   2. B140 J
   3. C200 J
   4. D120 J
   ( )
5. 5

   The power of an appliance is the

   1. Atotal energy it stores
   2. Bforce it exerts per metre
   3. Cvoltage it needs per amp
   4. Denergy it transfers per second
   ( )
6. 6

   A 950 W microwave runs for 2.0 minutes. The energy transferred is

   1. A114 000 J
   2. B1 900 J
   3. C47.5 J
   4. D950 J
   ( )
7. 7

   Adding lagging around a hot water tank reduces the rate of energy transfer by

   1. Aconduction and convection
   2. Bnuclear decay
   3. Celectrical working
   4. Drefraction
   ( )
8. 8

   The kinetic energy of a 500 kg car moving at 20 m/s is

   1. A10 000 J
   2. B100 000 J
   3. C200 000 J
   4. D5 000 J
   ( )
9. 9

   A crane does 9 600 J of work in 16 s. Its useful power output is

   1. A153 600 W
   2. B16 W
   3. C600 W
   4. D0.6 W
   ( )
10. 10

    In the specific-heat-capacity practical, wrapping the block in insulation improves the result because it

    1. Aincreases the block’s mass
    2. Braises the room temperature
    3. Creduces energy dissipated to the surroundings
    4. Dmakes the joulemeter more accurate
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 11

   A student rides a bicycle along a flat road, then brakes to a stop at a junction.

   1. (a)

      Name the main store that empties while the student pedals and the main store that fills.

      [2]
   2. (b)

      When braking, describe the energy transfer that slows the bicycle.

      [2]
   3. (c)

      Explain why the bicycle never returns 100% of the pedalling energy as forward motion.

      [1]
2. 12

   This question is about household energy use. A family’s electric oven is rated at 3.0 kW and runs for 40 minutes.

   1. (a)

      Calculate the energy the oven transfers, in joules.

      energy =[3]
   2. (b)

      Of the energy in (a), 6 120 000 J cooks the food. Calculate the oven’s efficiency.

      efficiency =[2]
   3. (c)

      Explain one way the oven’s efficiency could be improved, naming the transfer that is reduced.

      [2]
   4. (d)

      The family also uses a 2.0 kW kettle for 4 minutes each day. Calculate the energy it uses in one week, in kilowatt-hours.

      weekly energy =[2]
3. 13

   A student measures the specific heat capacity of copper using a 2.0 kg block, a 50 W heater, a joulemeter and a thermometer. The heater runs for 4.0 minutes and the temperature rises from 20 °C to 78 °C.

   Readings

   Quantity	Value
   Mass of block	2.0 kg
   Heater power	50 W
   Heating time	4.0 min
   Starting temperature	20 °C
   Finishing temperature	78 °C

   1. (a)

      Calculate the energy supplied to the heater.

      [1]
   2. (b)

      Calculate the specific heat capacity from these results.

      c =[2]
   3. (c)

      The accepted value for copper is 385 J/kg °C. Explain why the student’s value is different.

      [2]
   4. (d)

      State one improvement that would make the measurement closer to the accepted value.

      [1]