Three children are riding on the edge of a merrygoround that

Three children are riding on the edge of a merry-go-round that is 105 kq, has a 1.50-m radius, and is spinning at 22.0 rpm. The children nave masses of 22.0, 28.0, and 33.0 kg. If the child who has a mass of 28.0 kg moves to the center of the merry-go-round, what is the new angular velocity in rpm? Ignore friction, and assume that the merry-go-round can be treated as a solid disk and the children as points.

Solution

conserving angular momentum

(105/2 + 22+28+33 ) r^2 x w1 = ( (105/2 + 22+33) w2 x r^2

w2 = 1.26 w1

w2 = 1.26*22 =  27.72 rpm