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8 Energy – forces doing work

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Question 94
H

A motor operates for 10 s at an input power of 400 W and an efficiency of 0.75. It then operates for 20 s at an input power of 200 W and an efficiency of 0.50. What is its overall efficiency for the full 30 s?

[1]
A

66.7%66.7\%66.7%

B

60.0%60.0\%60.0%

C

62.5%62.5\%62.5%

D

58.3%58.3\%58.3%

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8 Energy – forces doing work Questions

  1. GCSE
  2. /Physics
  3. /8 Energy – forces doing work

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