Hi:(adsbygoogle = window.adsbygoogle || []).push({});

Would somebody please check to see if I am on the right track with this problem.

Many thanks

1. The problem statement, all variables and given/known data

An 80kg man on a step-exercise machine climbs a staircase 3.0m high in 8.5s. If he works at the same rate to drive a pedal-operated generator with an efficiency of 75%, how much electrical power would be produced?

2. Relevant equations

power=work done/time taken

efficiency=useful energy output/total energy input

work=force x displacement in direction of force

F=ma

weight=mg (gravity=10ms ^-2)

3. The attempt at a solution

F=80 x 10 =800N

Work done (W)=800 x 3.0 = 2400J

Power=2400/8.5 = 282.4W (1d.p.)

therefore

75% x 282.4 = 211.8W

F=

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# Homework Help: Electrical power

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