Abook weighs 0.5 kilograms on a book shelf that is 2 meters above the ground. what is the potential energy of the book relative to the ground? (hint: you may use 10 n/kg as the value for gravity)

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.