A hollow rod has frictionless inner walls. Inside the rod are two small spheres that are kept on either side of the centre of rod. The rod is rotated about its central axis which is perpendicular to the plane of rotation. If the rod had been rotated by an impulsive torque which gave it an instantaneous angular velocity of 5rad/s, what will be the angular velocity after some finite but long time t ? Assume no external forces act on rod after the impulse. Also state what will happen to the spheres in the centre of the rod. The rod has a mass =2kg & length =10cm. The two spheres have a mass =1kg each.

• A. 2.5 rad/s, spheres will stay where they are as there is no friction to move them
• B. 0 rad/s, spheres will move outwards and decrease velocity of rod to zero
• C. 1.25 rad/s, spheres will move to opposite ends of rod
• D. 2.5 rad/s, spheres will move to opposite ends of rod