Question

How much work is done lifting a 10 pound object from the ground to the top of a 45 foot building if the cable used weighs 1.5 pounds per foot?

Answer 1

The work is given by:

$W=F\cdot\Delta x$

Where:

$\begin{gathered} F=Force \\ \Delta x=Distance \end{gathered}$

In this case the force is given by:

$\begin{gathered} 9.8m/s^2\times\frac{3.28ft}{1m}=32.144ft \\ so: \\ W=10(32.144)+45\cdot(1.5)=388.94 \\ \Delta x=45ft \\ hence: \\ W=388.94\cdot45=17502.3ft-lb \end{gathered}$

Answer:

17502.3 lb