Find the work $($in ft$-$lb$)$ done by winding up a hanging cable of length $100$ ft and weight$-$density $3$ lb$/$ft$.$

ft$-$lb

How much work $($in ft$-$lb$)$ is done to lift the cable $50$ ft$?$

ft$-$lb

How much additional work $($in ft$-$lb$)$ is done when winding up the cable of length $100$ ft by hanging a $900$ lb weight at the end of the cable?

ft$-$lb