Rankers Physics

A disc is rotating with angular speed $\omega$. If a child sits on it, what is conserved: (2002)

Linear momentum
Angular momentum
Kinetic energy
Potential energy

Solution:

When the child sits on the rotating disc gently, no external torque acts on the system.
According to Newton's second law for rotation, if net external torque is zero, the total angular momentum of the system remains conserved.

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