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8 Energy – forces doing work

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Question 1

An escalator runs for 30 s while carrying passengers to a higher floor.

The escalator has a constant input power of 8.0 kW. During this time, it transfers 180 kJ usefully to the gravitational energy stores of the passengers.

The bearings are then replaced. The input power remains the same, but the total power dissipated in unwanted transfers is 0.80 kW less than before.

a.

Calculate the efficiency of the escalator before the bearings are replaced.

[3]
b.

Calculate the efficiency of the escalator after the bearings are replaced.

[2]
Markscheme

8 Energy – forces doing work Questions

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

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