1. 1
   A quarry crane lifts a 500 kg block of stone from ground level to a height of 8 m at a steady speed, taking 10 s to complete the lift. Take gravitational field strength g = 9.8 N/kg.

   (a)

   As the block rises, which energy store increases?

   [1 mark]

   • AThe kinetic energy store of the block
   • BThe gravitational potential energy store of the block
   • CThe chemical energy store of the block
   • DThe elastic potential energy store of the block

   (b)

   Which equation should be used to calculate the useful work done by the crane motor in lifting the block to height h?

   [1 mark]

   • AW = Fs, where F is the weight of the block and s is the height risen
   • BW = ma, where a is the acceleration of the block
   • CW = Q/t, where Q is the charge moved
   • DW = 1/2 k e^2, where e is the extension

   (c)

   Calculate the gravitational potential energy gained by the block as it is lifted to a height of 8 m. Give your answer in joules, including the equation used and your working.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A blacksmith heats a 2 kg iron bar from 20°C to 820°C in a forge. The specific heat capacity of iron is 450 J/kg°C.

   (a)

   Which energy store of the iron bar increases as it is heated?

   [1 mark]

   • AThe kinetic energy store only
   • BThe elastic potential energy store
   • CThe gravitational potential energy store
   • DThe thermal energy store

   (b)

   Which statement correctly defines the specific heat capacity of iron used above?

   [1 mark]

   • AThe energy needed to change the state of 1 kg of iron with no change in temperature
   • BThe total energy stored in 1 kg of iron at room temperature
   • CThe energy needed to raise the temperature of 1 kg of iron by 1°C
   • DThe energy released when 1 kg of iron cools to 0°C

   (c)

   Calculate the energy transferred to the iron bar's thermal energy store as it is heated from 20°C to 820°C. Give the equation used, your working, and the final answer with unit.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A gymnast on a trampoline stretches the trampoline bed downwards as she lands, then is launched back upwards. The trampoline bed behaves like a spring with a spring constant of 5000 N/m and stretches by 0.4 m when she lands, within the limit of proportionality.

   (a)

   Explain, in terms of energy stores, what happens to the gymnast's energy from the moment she lands on the bed to the moment she reaches the top of her bounce. Include a description of the role of the trampoline bed.

   [3 marks]

   (b)

   The trampoline bed behaves like a spring with a spring constant of 5000 N/m. When the gymnast lands, the bed stretches by 0.4 m, within the limit of proportionality. Calculate the elastic potential energy stored in the trampoline bed at maximum stretch, and state one reason why, in reality, slightly less than this amount of energy is transferred back to the gymnast.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A roller coaster carriage of mass 600 kg is pulled to the top of the first hill, 45 m above the lowest point of the track, and then released from rest to travel around the rest of the circuit. Engineers designing a new roller coaster want later hills to be built closer in height to the first hill.

   (a)

   Explain, using the idea of energy stores and transfers, how the carriage is able to travel around the whole circuit, and why later hills on the track must be lower than the first hill. Include a calculation of the maximum possible speed of the carriage at the lowest point of the track, assuming no energy is transferred to the thermal energy store due to friction or air resistance.

   [6 marks]

   (b)

   Engineers are designing a new roller coaster and want to reduce the energy transferred to the thermal energy store due to friction between the carriage wheels and the track, so that later hills can be built closer in height to the first hill. Evaluate two engineering methods they could use to achieve this, explaining how each method reduces unwanted energy transfer, and discuss one limitation of each method.

   [6 marks]

   Total for question 4: 12 marks

End of questions