Aplayground merry-go-round has a radius of 3.0 m and arotational inertia of 600 kg ⋅ m2. it
is initially spinning at 0.80 rad/s when a 20-kg child crawlsfrom the center to the rim. when
the child reaches the rim the angular velocity of themerry-go-round is:
a) 0.61 rad/s
b) 0.73 rad/s
c) 0.80 rad/s
d) 0.89 rad/s
e) 1.1rad/s

Final angular velocity,

Explanation:

Given that,

Radius of merry- go- round, r = 3 m

Inertia of the merry- go- round,

Angular speed,

Mass, m = 20 kg

Let I' is the new rotational inertia of the merry- go- round. Here, the angular momentum of the system remains conserved. So,

So, the angular velocity of the merry-go-round is 0.61 rad/s. So, the correct option is (A). Hence, this is the required solution.

pe = weightxheight = 2000x1000=2,000,000joules