Problem # p008

Work-Energy Method


The rope ABC is attached to the wall at point A and runs over the smooth (frictionless) peg B which is part of the 80 kg cart shown. A constant vertical force P=100 N is applied at the end C of the rope. The cart is initially (t=0) at rest (v=0) when x=5m. Neglect friction at the pulley and between the cart and the floor.
Determine the speed of the block when it hits the wall (x=0). Use the work-energy principle. Caution: by how much will force P move downwards ?