Well, TOKRB_ApplyImpulse always applys an impulse at the center of the rigidbody, thus no rotation is imparted. TOKRB_ApplyImpulse 2 on the other hand can apply an impulse anywhere, so, if not applied to the center, rotation is imparted. Note that the last three parameters are global so if you want to apply an impulse at an offset you will have to add the position of the rigid body to the offset.