Pearson Edexcel International GCSE
Physics — Topic 4 Paper 2
Energy resources and energy transfers · specification 4.1–4.17
Time allowed: 30 minutes
Total marks: 25
Candidate name:
Centre / class:
Answer all questions. You may use a calculator. Show your working. Take $g=10\,\text{N/kg}$.
1
A filament lamp is supplied with $60\,\text{J}$ of electrical energy. $12\,\text{J}$ is transferred usefully as light. $48\,\text{J}$ is wasted as thermal energy.
(a) Calculate the efficiency of the lamp.
[2]
(b) On a Sankey diagram, which arrow should be the widest: the input, the useful output, or the wasted output? Explain your answer.
[2]
(c) Name the pathway for the useful transfer and the store that increases because of the wasted $48\,\text{J}$.
[2]
(Total for Question 1 = 6 marks)
2
A skateboarder of mass $50\,\text{kg}$ starts from rest at a height of $3.2\,\text{m}$ above the bottom of a ramp.
(a) Calculate the gravitational potential energy store at the top of the ramp.
[2]
(b) On the way down, friction transfers $400\,\text{J}$ to the thermal store of the wheels and air. Calculate the kinetic energy at the bottom.
[2]
(c) Calculate the speed of the skateboarder at the bottom.
[3]
(Total for Question 2 = 7 marks)
3
A room is heated by an electric heater placed on the floor near one wall.
(a) Explain how a convection current is set up in the room. Refer to density in your answer.
[4]
(b) Suggest why the heater is placed near the floor rather than on the ceiling.
[2]
(Total for Question 3 = 6 marks)
4
A student compares how well different metals conduct thermal energy. She uses rods of copper, aluminium and iron. A drawing pin is attached to the end of each rod with wax. The other ends are heated together.
(a) Describe a method the student should use. State the independent variable, the dependent variable, and two quantities she must control.
[4]
(b) State one safety precaution and one reason a pin might fall at the wrong time, giving a false result.
[2]
(Total for Question 4 = 6 marks)
END OF PAPER 2