Q.45 A curved surface is shown in the figure. The portion BCD is free of friction. There are three spherical balls of identical radii and masses. Balls are released from rest one by one from A which is at a slightly greater height than C.
With the surface AB, ball 1 has large enough friction to cause rolling down without slipping; ball 2 has small friction and ball 3 has negligible friction.
(a) For which balls are total mechanical energy conserved?
(b) Which ball (s) can reach D?
(c) For balls that do not reach D, which of the balls can reach back A?
(a) As ball 1 is rolling down without slipping there is no dissipation of energy hence. total mechanical energy is conserved.
Ball 3 is having negligible friction hence, there is no energy loss.
(b) Ball 1 acquires rotational energy, ball 2 loses energy by friction. They Cannot cross at C. Ball 3 can cross over.
(c) Ball 1, 2 turns back before reaching C. Because of Joss of energy, ball 2 cannot reach back to A. Ball 1 has a rotational motion in the "wrong" sense when it reaches B. It cannot roll back to A, because of kinetic friction.
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