A child is standing with folded hands at the centre of a platform rotating about its central axis. The kinetic energy of the system is K. The child now stretches his arms so that moment of inertia of the system becomes four times. The kinetic energy of the system now is

A child is standing with folded hands at the center of a platform rotating about its central axis. The kinetic energy of the system is K . The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is: a) K/4 b) K/2 c) 2K d) 4K

A child is standing with his two arms outstretched at the centre of a turntable that is rotating about its central axis with an angular speed omega_0 . Now, the child folds his hands back so that moment of inertia becomes 3 times the initial value. The new angular speed is.

A horizonral circular plate is rotating about a vertical axis passing through its centre with an angular velocity omega_(0) . A man sitting at the centre having two blocks in his hands stretches out his hands so that the moment of inertia of the system doubles. If the kinetic energy of the system is K intially, its final kinetic energy will be

A fly wheel rotating about a fixed axis has a kinetic energy of 360 J . When its angular speed is 30 rad s^(-1) . The moment of inertia of the wheel about the axis of rotation is

A fly wheel rotating about a fixed axis has a kinetic energy of 360 J . When its angular speed is 30 rad s^(-1) . The moment of inertia of the wheel about the axis of rotation is

A flywheel rotating about a fixed axis has a kinetic energy of 360J when its angular speed is 30 radian s^(-1) . The moment of inertia of the wheel about the axis of rotation is

A boy stands over the centre of a horizontal platform which is rotating freely with a speed of 2 "revolutions"//s about a vertical axis through the centre of the platform and straight up through the boy. He holds 2 kg masses in each of his hands close to his body. The combined moment of inertia of the system is 1 kg xx metre^(2) . The boy now stretches his arms so as to hold the masses far from his body. In this situation, the moment of inertia of the system increases to 2 kgxxmetre^(2) , The kinetic energy of the system in the latter case as compared with that in the previous case will

A child of mass m is standing, on the periphery of a circular platform of radius R , which can rotate about its central axis. The moment of inertia of the platform is I . Child jumps off from the platform with a velocity u tangentially relative to the platform. Find the angular speed of the platform after the child jumps off.

A body is rotating with angular momentum L. If I is its moment of inertia about the axis of rotation is I, its kinetic energy of rotation is

In Fig. a man stands on a boat floating in still water. The mass of the man and the boat is 60 kg and 120 kg , respectively. a. If the man walks to the front of the boat and stops. what is the separation between the boat and the pier now? b. If the man moves at a constant speed of 3 m//s relative to the boat, what is the total kinetic energy of the system (boat + man)? Compare this energy with the kinetic energy of the system if the boat was tied to the pier.