A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration $${a_c}$$ is varying with time t as $${a_c}$$ = k²rt² where k is a constant. The power delivered to the perticles by the force acting on it is:

If a machine is lubricated with oil

Two masses of 1gm and 4 gm are moving with equal kinetic energies. The ratio of the magnitude of their linear momentum is