[" If "vec tau timesvec L=0" for a rigid body,"],[" where "vec tau=" resultant torque "&vec L=],[" angular momentum about a "],[" point and both are non-zero."],[" Then: "]

If vec(tau)xxvec(L)=0 for a rigid body, where vec(tau)= resultant torque & vec(L) =angular momentum about a point and both are non-zero. Then

If vec(tau)xxvec(L)=0 for a rigid body, where vec(tau)= resultant torque & vec(L) =angular momentum about a point and both are non-zero. Then

The correct relation between torwue tau and angular momentum L is

Torque (vec tau) acting on a rigid body is defined as vec tau = vec A xx vec L , where vec A is a constant vector and vec L is angular momentum of the body. The magnitude of the angular momentum of the body remains same. vec tau is perpendicular to vec L and hence torque does not deliver any power to the body.

Obtain tau=Ialpha from angular momentum of rigid body.

If vec r* vec a =0 = vec r* vec b ,where vec a and vec b are non-coplanar vectors then

The torque vec tau on a body about a given point is found to be equal to vec A xx vec L where vec A is a constant vector and vec L is the angular momentum of the body about the point. From this its follows that -

The torque tau on a body about a given point is found to be equal to AxxL where A is a constant vector, and L is the angular momentum of the body about that point. From this it follows that