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Question:

A crane uses 2 kW to raise a 100-kg box 20 meters. How much time does it take?

I'm not sure how to set this problem up. Any help would be greatly appreciated. Thank you :)

Answer:

We start using by defining mechanical Power: = P=Work/time What is the work here? We lift the box a given distance. Work=mgh Since we know the power of the crane, we can simply plug in the values and solve for t: t=mgh/P This is only true if the crane has a constant power, which seems to be the case LeSmartOne

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