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Question
An electric motor drives a machine which lifts a mass of 4 kg through a height of 10 m in 5 s at a constant speed. Assuming g = 10 ms-2, calculate
(i) the amount of work done, (ii) the power of the machine.
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Solution
Given mass m = 4 kg,height h = 10m, time t = 5s
(i) work done = mgh = 4 x 10 x 10 = 400 j
(ii) power = `"work done"/"time taken" = 400/5` = 80 w
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