A roundabout whose rotating base is a heavy uniform disc of radius 2m and mass 400 kg has a central pillar and handles which are of negligible mass (see figure). The roundabout is set rotating at a steady rate of 20 r.p.m. E 20 r.p.m. Four small children, of mass 10 kg, 20 kg, 30 kg and 40 kg respectively, step gently on the edge of the roundabout, each with velocity 7.2 km/hr along a tangential direction and cling to the handles. After holding on for sometime, the children step gently off the roundabout with the same velocity but this time in a radial direction. Neglecting all effects of friction and air drag, the final rate of rotation of the roundabout will be about (a) 28 r.p.m. (c) 36 r.p.m. (b) 25 r.p.m. (d) 21 r.p.m.

A roundabout whose rotating base is a heavy uniform disc of radius 2m and mass 400 kg has a central pillar and handles which are of negligible mass (see figure). The roundabout is set rotating at a steady rate of 20 r.p.m. E 20 r.p.m. Four small children, of mass 10 kg, 20 kg, 30 kg and 40 kg respectively, step gently on the edge of the roundabout, each with velocity 7.2 km/hr along a tangential direction and cling to the handles. After holding on for sometime, the children step gently off the roundabout with the same velocity but this time in a radial direction. Neglecting all effects of friction and air drag, the final rate of rotation of the roundabout will be about (a) 28 r.p.m. (c) 36 r.p.m. (b) 25 r.p.m. (d) 21 r.p.m.