Newton’s Law of Motion Impulse
Sometimes a large force acts for a very short duration and produces a finite change in momentum of the body. For example, hitting a cricket ball by a bat. Here, the ball is reflected back and the force on the ball acts for a very short time when the two are in contact. Practically, it is not possible to measure either the magnitude of force or the time for which it acts. In such a case, the total effect of force is measured by the impulse of the force. The impulse of the force is defined as the product of the force and its time of action.
If a force F acts on a body for a very short time t, then
Impulse= Force x time duration = F xt … = Change in momentum
The force acting for a short duration is called as impulsive force.
Impulse =p_2-p_1
Thus impulse of the force is equal to the total change in momentum of the body. Impulse is a vector quantity and its direction is same as that of force. The impulse of the force may be positive, negative or zero according as the momentum of the body increases, decreases or remains unchanged under the effect of force.
