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How long would it take a roofer to lift a load?

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A roofer lifts supplies to a height of 20m with a hand-operated wench. How long would it take him to lift a 200-kg load, if the wench has an efficency of 90%, and the rate at which the wench can do work is .8hp?

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This solution includes simple calculations and answer discovering how long it would take a roofer to lift a load.

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