Amount of work done (integration)
A cable that weighs 2ft/lb is used to lift 800lb of coal up a mine shaft 500ft deep. Find the work done. I can't figure out where to start. I understand that W=Fd.
I also have a problem trying to solve something that seems relatively simple: A particle is moved along the x-axis by a force that measures 10/(1+x)^2 lbs at a point x ft. from the origin. Find the work done in moving the particle from origin to a distance of 9 ft. For this, I set up the integral from 0 to 9 of 10/(1+x)^2 dx and solved, but did not get the final answer of 9ft*lb.