A circular platform is free to rotate in a horizontal plane about a 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),

Options

A.
B.
C.
D.

Answer

B

Explanation

Since there is no external torque angular momentum remains conserved. As momentum of inertia initially decreases and then increases, so `omega` will increase initially and then decrease.
Moment of inertia when tortoise is at `B`,
`I=mr^(2)+(MR^(2))/2`,
where `r^(2)=a^(2)+[sqrt(sqrt(2)-a^(2))-vt]^(2),m=`mass of tortoise,
`M=` mass of disc
Therfore, the variation of `omega` is non linear.