Question

A block and tackle of 6 pulleys is used to raise a load of 300 newton steadily through a height of 30 meters. If the work done against friction is 2000j calculate the work done by effort?

Answer 1

W = F * S = 300 N * 30 m = 9000 Joules

This is the work out of the system regardless of how the pulleys are arranged

Conservation of energy tells that

Work Out = Work In - Work done by friction

So Work In = 9000 J + 2000 J = 11000 J The work input to the system