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