Question

A chain 18 feet long whose weight is 84 pounds is hanging over the edge of a tall building and does not touch the ground. How much work is required to lift the entire chain to the top of the building

Answer 1

756 feet pound

Explanation:

Length of the chain, L = 18 feet

weight of chain, W = 84 pound

If we lift the centre of gravity of the chain, it will entirely lift up. The centre of gravity of the uniform chain is at its mid point. So, the work done

W = weight x half of length

W = 84 x 9

W = 756 feet pound