A person of mass 79kg stands at the center of a rotating merry-go-round platform

Question

A person of mass 79kg stands at the center of a rotating merry-go-round platform of radius 3.3m and moment of inertia 830kg?m2 . The platform rotates without friction with angular velocity 0.95rad/s . The person walks radially to the edge of the platform.

1. Calculate the angular velocity when the person reaches the edge.

Express your answer using three significant figures and include the appropriate units.

2.

Calculate the rotational kinetic energy of the system of platform plus person before and after the person's walk.

Express your answers using two significant figures. Enter your answers numerically separated by a comma.

Explanation / Answer

(a) Assuming the merry go round is freely rotating (not powered by a motor), then it's subject to the conservation of angular momentum:

I1 * w1 = I2 * w2

Its moment of inertia is:

I = I-disk + m*r

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