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8.3 Power and efficiency

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Question 32
F

A student measures her useful power output by running up a flight of stairs.

The Figure shows the stairs.

Figure

image

The mass of the student is 54 kg.

She takes 4.5 s to run from the start to the finish.

Gravitational field strength (ggg) = 10 N/kg

a.

Calculate the increase in gravitational potential energy of the student.

[2]
b.

Calculate the useful power output of the student.

[2]
c.

A second student has a mass of 72 kg. He takes 6.0 s to run up the same stairs.

He says:

'My power output is greater than hers because I do more work.'

Explain whether he is correct.

[3]
d.

The time is measured with a stopwatch.

Suggest one reason why the value of the power calculated may not be accurate.

[1]
Markscheme

8.3 Power and efficiency Questions

  1. GCSE
  2. /Physics
  3. /8.3 Power and efficiency

128 exam-style questions on Edexcel GCSE Physics 8.3 Power and efficiency, covering 8.3.1 Power and 8.3.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.

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