A body is rotating, it is necessary being acted upon by an exteral torque?

Amylopsin acts upon:

A rigid body is rotating about an axis. To stop the rotation, we have to apply

If net force acting on a body is zero, then will the body remain necessarily in rest position?

Calculate the force and torque acting on an electric dipole placed in an external unifrom electric field, and define dipole moment and explain when the torque is maximum and minimum.

A body of mass 20g is rotating around a pole 50 cm away with a frequency 5 r.p.s.Find the rotational kinetic energy of the body.

Find the amount of work done in rotating a magnet through an angle theta against the torque acting due to uniform magnetic field. What happens to the work done?

These are three forces F_1, F_2,F_3 acting on a body, all acting on a point P on the body. the body is found to move with uniform speed. Show that the torque acting on the body about any point due to these three forces is zero.