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.

S_(1): Net torque on a system due to all internal force about any poin

1.	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.
Answer» TFFF TTFT FFFF TFFT Solution :`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 anypoint is same.