The net work is thus the sum of the work done by the force gravity, Wg, and the work done by the force of friction, Wf, over the displacement corresponding to the length of the ramp: Thus th...The net work is thus the sum of the work done by the force gravity, Wg, and the work done by the force of friction, Wf, over the displacement corresponding to the length of the ramp: Thus the net work done by the force of friction is the difference in kinetic energies between the final landing point and the beginning of the ramp, because friction is the only force that did a net amount of (negative) work over the whole trajectory (gravity did no net work over the whole trajectory).
