Question

A circular platform is free to rotate in a horizontal plane about vertical axis passing through its centre. A tortoise is sitting at the edge of the platform. Now, the platform is given an angular velocity ${\omega }_0$. When the tortoise move along a chord of the platform with a constant velocity (with respect to the platform). The angular velocity of the platform $\omega \left(t\right)$ will vary with time t as

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Since net external force is zero, the angular momentum of platform+tortoise will remain constant. First, the moment of inertia will decrease, then increase. So, angular velocity will first increase, then decrease. Also, the variation will be non-linear.