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 ω 0 . When the tortoise moves along a chord of the platform with a constant velocity (w.r.t. the platform), which of the following graphs shows properly the variation of angular velocity of the platform with the t

Step-by-step solution

As there is no external torque, angular momentum will remain constant. When the tortoise moves from A to C , figure, moment of inertia of the platform and tortoise decreases. Therefore, angular velocity of the system increases. When the tortoise moves from C to B , moment of inertia increases. Therefore, angular velocity decreases If, M =mass of platform R = radius of platform m = mass of tortoise moving along the chord A B a = perpendicular distance of O from A B Initial angular momentum, I 1 = m R 2 + M R 2 2 At