The crate A of weight W = 30 lb is being pulled to the right by the winch at B. The crate...

The crate A of weight W = 30 lb is being pulled to the right by the winch at B. The crate starts from rest at x = 0 and is pulled a total distance of 15 ft over the rough surface for which the coefficient of kinetic friction is μk= 0.3. The force P in the cable due to the winch varies according to the plot, where P is in lb, b is in , and x is in ft. The coefficient of static friction is insufficient to prevent slipping.

Using the work-energy principle, determine the value of b so that the block is moving at 35 ft/s when x = 10 ft.

Figure P4.21