1 ) Consider a rigid body, composed of o = 1, 2, 3, ..., /V particles, moving with a velocity of V = R. while rotating about its centre of mass with an angular velocity w = wn. Z (0) V cm X Note that the velocity of the o'th particle of mass m is given by v =V +wnxr a) (4 marks) Show that the gravitational potential energy of the rigid body is U ora grav = MgZcm where M is its total mass and Z is the height of its centre of mass