Abrave child decides to grab onto an already spinning merry‑go‑round. the child is initially at rest and has a mass of 35.5 kg.
the child grabs and clings to a bar that is 1.25 m from the center of the merry‑go‑round, causing the angular velocity of the merry‑go‑round to abruptly drop from 43.0 rpm to 17.0 rpm .

what is the moment of inertia of the merry‑go‑round with respect to its central axis?

36.3 kgm2

Explanation:

According to the conservation of angular momentum, the angular momentum is preserved before and after the child grab. Since the moments of inertia increase, the angular velocity decreases.

Let I be the moment of inertia of the merry-go-round and treat the child as a point particle, his moment of inertia would be

Hence the moment inertia of the child-merry-go-round system is:

I + 55.5

From here we can apply the conservation theory

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.