A playground merry-go-round has a radius of 3.0 m and a rotational inertia of 600 kg .m². It is initially spinning at 0.80 rad/s when a 20-kg child crawls from the center to the rim. When the child reaches the rim the angular velocity of the merry-go-round is: A) 0.62 rad/s B) 0.73 rad/s C) 0.80 rad/s D) 0.89 rad/s E) 1.1 rad/s

Question

Quizplus · Accepted Answer

The angular momentum is conserved. Initially, the angular momentum is the product of the rotational inertia and the initial angular velocity. When the child moves to the rim, the new rotational inertia is the sum of the original rotational inertia and the child's mass times the square of the radius. Solving for the new angular velocity gives 0.62 rad/s.

A Playground Merry-Go-Round Has a Radius of 3