__Impulse of a Force:__

For a constant force acting on a body for an interval of time, the product of the force and the time interval is the impulse of the force.

Let us suppose that a body of mass m is being acted upon by a force F for time t.

∴ Impulsive force = F x t

As a result, the velocity of the body changes from u to v and its acceleration is a = (v – u)/t

Therefore, impulse of force = F.t = ma.t

= m.(v – u)/t x t

= m(v – u)

= mv – mu …equ(1)

= change in momentum

So, the change in momentum of a body is equal to the impulse of the force acting on it. Force and impulse are both vector quantities. Therefore, equation(1) is a vector equation and the direction of impulse is the same as that of the force itself.

## Unit of Impulse Force:

Impulse has the unit and dimension of momentum. SI unit of impulse force is **Newton-seconds** (**Ns**) or **kg m/s**. Dimension of impulse force is **MLT ^{-1}**