Child is pushing a cart across the floor, and the cart moves at a certain speed. When he pushes the cart with a greater force, the cart begins to move faster.
Which type of energy increases when the child applies a greater force?

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.