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A large force that acts on a body for a very short period of time is called an 'Impulsive force'.
When a force '\(F\)' acts on a body for a duration of time '\(t\)', then the product of force and time period is called 'impulse', represented by '\(J\).'
Impulse (J) = Force(F) × Time(t)...eqn(1
By Newton's second law,
Force(F) = Changeinmomentum(Δp)time(t) (Δ refers to changeΔp=F×t...eqn(2)
From equations (1) and (2)
 J = Δp
Impulse is also equal to the magnitude of change in momentum.
The SI unit of impulse is the \(newton-second\) (\(Ns\)) and the dimensionally equivalent unit of momentum is the \(kilogram meter per second\) (kgms1).
Change in momentum can be attained in two ways. They are:
  1. a large force acting for a short duration of time, and 
  2. a smaller force acting for a longer duration of time.
  • Automobiles are furnished with springs and shock absorbers to decrease jerks while moving on rough roads.
  • In cricket, while catching the ball, a fielder pulls back his hands. He experiences a smaller amount of force for a longer period of time to catch the ball, resulting in a much lesser impulse on his hands.