Question

To drive a nail into a wooden block, we blow a hammer on the nail. When a ball hits a wall, it bounces back In both of these examples, a large force acts for a very short duration producing a finite change in the momentum of the body. Here it is difficult to measure force and time separately. The product of the force and time that produces a finite change of momentum is called impulse. Impulse = Force x time duration = Total change in momentum. SI unit of impulse is Ns or kgm/s. It is a vector quantity having the direction same as that of force or the change in momentum. A large force acting force a short time is called an impulsive force. For a variable force, impulse J is given by J = P2 - P1 = ∫dp = ∫Fdt = Area under the force-time curve.

Assertion-When a fixed force is applied for a certain interval of time on two bodies of different masses initially at rest the lighter body picks up a greater speed than the heavier body Reason-Same force for the same time causes same change in momentum for different bodies