"A cylindrical tank of height h is half full of water, all of which is to be pumped up over the side of the tank. If the total mass of the water is m, how much work must be done by the pump?"(adsbygoogle = window.adsbygoogle || []).push({});

At first I tried this the easy way by simply assuming that I need to pump a mass m up to a height h, so the work would be just mgh, but somehow the result should be (3/4)mgh, I guess I have to account for the fact that not all the water comes from the same height, I however have no idea how to express this mathematically.

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# Work by a variable force

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