Pearson Edexcel International GCSE
Physics — Topic 4 Paper 1
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
The Sankey diagram for an electric kettle is labelled $2000\,\text{J}$ input, $1600\,\text{J}$ useful thermal energy transferred to the water, and $400\,\text{J}$ wasted.
(a) Calculate the efficiency of the kettle.
[2]
(b) State the useful energy store that increases and the pathway by which energy is transferred to the kettle.
[2]
(c) Name the store that decreases to supply the $2000\,\text{J}$, and state where the wasted $400\,\text{J}$ goes.
[2]
(Total for Question 1 = 6 marks)
2
A brick of mass $2.0\,\text{kg}$ is held at rest $5.0\,\text{m}$ above the ground.
(a) Calculate the gravitational potential energy store of the brick relative to the ground.
[2]
(b) The brick is dropped. Air resistance is negligible. State the kinetic energy just before it hits the ground and calculate its speed.
[3]
(c) In a second drop, work done against friction is $20\,\text{J}$. Calculate the kinetic energy just before impact.
[2]
(Total for Question 2 = 7 marks)
3
A student uses a vacuum flask to keep tea hot. The flask has a double silvered wall with a vacuum between the walls, and a plastic stopper.
(a) Explain how the vacuum reduces thermal energy transfer from the tea.
[2]
(b) Explain how the silvering reduces thermal energy transfer.
[2]
(c) Explain the purpose of the stopper.
[2]
(Total for Question 3 = 6 marks)
4
A student investigates how the surface of an object affects the infrared radiation it emits. She uses a Leslie’s cube filled with very hot water. The four faces have different surfaces, including dull black and shiny silver.
(a) Describe a method the student should use to compare the radiation from two faces. Include what she measures and what she keeps the same.
[4]
(b) Suggest two sources of error in this investigation and how one of them could be reduced.
[2]
(Total for Question 4 = 6 marks)
END OF PAPER 1