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 When the tortoise moves along a chord of platform with a constant velocity (with respect to the platform), the angular velocity of the platform (t) will vary with time t as
Since no external torque is acting on the system , its angular momentum remains conserved . So IDuring motion along chord, the distance of tortoise from centre decreases initially and then increases' So, the moment of inertia first decreases and then increases. Hence initially increase and then decrease. Also variation in is non-linear.