Hello victorxz90044Here are the steps you need to solve the problem:

- Consider a horizontal cross-section through the water at a height above the base, and with thickness .

.- Work out the area of this cross-section in terms of , and hence its mass in terms of and .

.- This mass of water is raised through a vertical height of feet. Find an expression for the work done, , when this happens.

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- Write down an expression for , and hence, by integrating between and , evaluate the total work done.

Can you do this now? Let us know where you got stuck, if not.

Grandad