Problem 1.121

A body of mass \(m\) was slowly hauled up the hill (Fig. 1.29 ) by a force \(\mathbf{F}\) which at each point was directed along a tangent to the trajectory. Find the work performed by this force, if the height of the hill is \(h,\) the length of its base \(l,\) and the coefficient of friction \(k\).