Question

A body of mass 3 kg is under a force, which causes a displacement in it is given by S = t³/3 (in m). Find the work done by the force in first 2 seconds.

A porter pushes a trunk on a railway platform which has a rough surface. He applies a force of 100 N over a distance of 10 m. Thereafter, He gets progressively tired and his applied force reduces linearly with distance to 50 N. The total distance through which the trunk has been moved is 20 m. Plot the force applied by the woman and the frictional force, which is 50 N versus displacement. Calculate the work done by the two forces over 20 m.