If a child walks toward the center of a merry-go-round, does the moment of inertia increase or decrease?

When a child walks toward the center of a merry-go-round, the moment of inertia decreases.

The moment of inertia, denoted by

I, is a measure of an object's resistance to changes in its rotational motion. It depends on both the mass and the distribution of mass about the axis of rotation.

As the child walks toward the center of the merry-go-round, the distribution of mass changes. By moving closer to the axis of rotation, the child effectively reduces the average distance of the mass from the axis. Since moment of inertia is directly proportional to the square of the distance from the axis of rotation, reducing this distance decreases the moment of inertia.

Therefore, as the child walks toward the center of the merry-go-round, the moment of inertia decreases.