A curved surface is shown figure . The portion BCD is free of friction .There are three spherical balls of identical radii and masses . Balls are released from at rest one by one from A which is at a slighly greater height than C . with the surface Ab , ball 1 has large eneough friction to cause rolling down without slipping , ball 2 has a small friction and ball 3 has a negligible friction . (a) For which balls is total mechanical energy conserved ? (b) Which ball (s) can reach D ? (c ) For ball which do not reach D, which of the balls can reach back A ?

A curved surface is shown figure . The portion BCD is free of friction

1.	A curved surface is shown figure . The portion BCD is free of friction .There are three spherical balls of identical radii and masses . Balls are released from at rest one by one from A which is at a slighly greater height than C . with the surface Ab , ball 1 has large eneough friction to cause rolling down without slipping , ball 2 has a small friction and ball 3 has a negligible friction . (a) For which balls is total mechanical energy conserved ? (b) Which ball (s) can reach D ? (c ) For ball which do not reach D, which of the balls can reach back A ?
Answer» Solution :(a) As ball 1 is rolling down withut slipping no disipation of ENERGY is there , total mechanical energy REMAINS UNCHANGED. Hence , it is conserved . (b) Ball 1 GAINS rtational energy , ball 2 loses energy due to friction . They cannot CROSS at C . Ball