What is torque? Explain the torque acting on a particle.

Explanation

Internal force of mutual interactions among the particles of a system are equal in magnitude and opposite in direction. Therefore the resultant torque due to them is zero. So we shall ignore the internal forces.
Suppose `vec(F_(1)),vec(F_(2)),vec(F_(3))....vec(F_(n))` are the external forces acting on the particles having position vectors `vec(r_(1)),vec(r_(2)),vec(r_(3))....vec(r_(n))`.
The resultant torque acting on the system is the vector sum of torque acting on the particles.
`therefore` Resultant torue
`vectau=vec(r_(1))xxvec(F_(1))+vec(r_(2))xxvec(F_(2))+......+vec(r_(n))xxvec(F_(n))`
`therefore vectau=vectau_(1)+vectau_(2)+............+vectau_(n)`