
The torque or the rotating force acting on a particle with respect to the origin of the reference frame is defined as
where r = the position vector of the particle, and F = the force acting on the particle. [1] can be rewritten as
since
[2] can be rewritten as
where
H shown in [4] & [5] is the angular momentum of the particle. Angular momentum is defined as the amount of the angular motion. From [4]: where t = the time, t_{o} = the initial time, and H_{o} = the initial angular momentum at t_{o}. From [6], the angular impulse is the accumulated effect of the torque exertion on the particle:

© YoungHoo Kwon, 1998 