`S_(1)`: Net torque on a system due to all internal force about any point is zero.
`S_(2)`: For rigid body undergoing fixed axis rotation, the direction of its angular acceleration and angular velocity
`S_(3)`: if net torque on a rigid body about its centre of mass is zero, the angular speed of the rigid body is always zero.
`S_(4)`: For a rigid body undergoing fixed axis rotation abouts its centre of mass, then net torque on rigid body about any point is same.

Options

A. TFFF
B. TTFT
C. FFFF
D. TFFT

Answer

D

Explanation

`S_(1)`: The line of action of each action reaction pair is same. Therefore magnitude of couple of each such pair is zero. Hence net torque of all internal force is zero.
`S_(2)`: if net torque on a rigid body is zero, its angular velocity will be constant. the constant may necessary down.
`S_(3)`: If net torque on a rigid body is zero, its angular velocity will be constant. the constant may necessary not zero.
`S_(4)`: since the centre of mass is fixed, that is, at rest, hence net force on rigid body is zero. therefore torque on this rigid body any point is same.