Question

Suppose you are standing on the edge of a spinning platform and step off at right angles to the edge (radially outward). Now consider it the other way. You are standing on the ground next to a spinning carousel and you step onto the platform at right angles to the edge (radially inward).
A. There is no change in rotational speed of the carousel in either situation.
B. There is a change in rotational speed in the first situation but not the second.
C. There is a change in rotational speed in the second situation but not the first.
D. There is a change in rotational speed in both instances

Answer 1

Correct Answer - C
In first case the impulse on the platform will act radially inward and it will not produce any angular impulse.
In second case, when man steps into platform, moment of inertia of system increases, so rotational speed decreases.