Impulsive force in mechanics is the change in linear momentum of an object
Suppose the force F is very large and acts for a very short time. During this time the distance moved is very small and under normal analysis would be ignored. Under these conditions the only effect of the force can be measured in is the impulse, or change in the momentum - the force is called an impulsive force.
The force that two colliding bodies exert on one another acts only for a short time, giving a brief but strong push. This force is called an impulsive force. During the collision, the impulsive force is much stronger than any other forces that may be present; consequently, the impulsive force produces a large change in the motion while the other forces produce only small and insignificant changes. For example, during the automobile collision shown in Figure 11.1, the only important force is the