AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Power
Power · Energy · Lesson 4 of 7 · 14 marks · 15 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 CALCULATE (2 marks)
A motor transfers 6000 J of energy in 30 s. Calculate the power of the motor. Use the equation: power = energy transferred ÷ time
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(Total for Question 1 = 2 marks)
Question 2 CALCULATE (2 marks)
A machine does 900 J of work in 12 s. Calculate the power.
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(Total for Question 2 = 2 marks)
Question 3 COMPARE (3 marks)
Motor A lifts a 20 N weight through 3.0 m in 6.0 s. Motor B lifts the same weight through the same height in 3.0 s. Compare the power of the two motors. Show your calculations.
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(Total for Question 3 = 3 marks)
Question 4 STATE (1 mark)
State what is meant by a power of 1 watt.
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(Total for Question 4 = 1 mark)
Question 5 CALCULATE (4 marks)
A person of mass 60 kg climbs stairs of height 3.0 m in 5.0 s. Calculate the power developed by the person. Gravitational field strength = 9.8 N/kg. Give your answer to 2 significant figures.
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(Total for Question 5 = 4 marks)
Question 6 CALCULATE (2 marks)
A 1500 W heater is switched on until it has transferred 450 000 J. Calculate the time it is switched on for.
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(Total for Question 6 = 2 marks)
TOTAL FOR PAPER = 14 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
6000 ÷ 30 = 200 W
• Correct substitution 1 mark
• 200 W 1 mark
Question 2 (2 marks)
900 ÷ 12 = 75 W
• Correct substitution 1 mark
• 75 W 1 mark
Question 3 (3 marks)
Work done = 20 × 3.0 = 60 J. Power A = 60 ÷ 6.0 = 10 W. Power B = 60 ÷ 3.0 = 20 W. Motor B has twice the power of motor A.
• Work done = 60 J 1 mark
• A = 10 W and B = 20 W 1 mark
• B has twice the power 1 mark
Question 4 (1 mark)
An energy transfer of 1 joule each second.
• 1 joule per second 1 mark
Question 5 (4 marks)
W = 60 × 9.8 × 3.0 = 1764 J; P = 1764 ÷ 5.0 = 352.8 W = 350 W
• Work done = mgh 1 mark
• 1764 J 1 mark
• 352.8 W 1 mark
• 350 W 1 mark
Question 6 (2 marks)
t = 450 000 ÷ 1500 = 300 s
• Rearranges to t = E ÷ P 1 mark
• 300 s 1 mark