How Much Work Is Required to Lift a 25-ft Chain Up a Building?

[fubag]

How much work is done lifting a 25-ft chain over the side of a building? Assume that the chain has a density of 4 lb/ft. Hint: Break up the chain into N segments, estimate the work performed on a segment, and compute the limit as N approaches infinity as an integral.


(The small segment of the chain of length delta y located y feet from the top is lefted through a vertical distance y.)

Force = g*density*volume...?

whats the volume of a segment of the chain, I am having difficulty.


please help

 

[fresh_42]

Volume is wrong here. It has to be mass: $(25ft. \cdot \;4 lb./ft.)/N$.