Chapter 7, Problem 90AP

A crate of mass 200 kg is to be bright from a site on the ground floor to a third floor apartment. The workers know that they can either use the elevator first, their slide it along the third floor to the apartment, or first slide the crate to another location marked C below and then take the elevator to the third floor and slide it on the third floor a shorter distance. The trouble is that the third floor is very rough compared to the ground floor. Given that the coefficient of kinetic Motion between the crate and the ground floor is 0.100 and between the crate and the third floor surface is 0.300, find the work needed by the workers for each path shown from A to E. Assume that the force the workers need to do is just enough to slide the crate at constant velocity (zero acceleration). Note: The work by the elevator against the force of gravity is not done by the workers.