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3.2 Dissipation and efficiency

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Question 14

An electric lawnmower is used to cut grass. During each second of use, the energy supplied to the lawnmower is transferred in the ways shown.

Energy transferEnergy transferred
to the kinetic energy store of the blades550 J
to the thermal energy stores of the motor and surroundings400 J
by sound50 J

What is the efficiency of the lawnmower?

[1]
A

45%45\%45%

B

55%55\%55%

C

58%58\%58%

D

92%92\%92%

Markscheme

3.2 Dissipation and efficiency Questions

  1. GCSE
  2. /Physics
  3. /3.2 Dissipation and efficiency

100 exam-style questions on Edexcel GCSE Physics 3.2 Dissipation and efficiency, covering 3.2.1 Dissipation of energy, 3.2.2 Reducing unwanted energy transfers, 3.2.3 Efficiency, and 3.2.4 Increasing efficiency. Each one has a worked solution and a mark scheme showing where the marks go.

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