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application of impulsive force? give example

Impulse

Impulse is defined as the effect of a force on a body which acts on it for a short interval of time. Impulse is equal to the product of force and the time interval

Therefore I = F x t

It is a vector quantity. Its direction is the same as that of the force. Its SI unit is Ns. 

According to Newton's Second Law

  is the momentum of body at any time t and  is the applied force at that time.

or     

Integrating both sides with limit,

Where  is the momentum at t = 0 and  is the momentum at time t. 

or           

or                     .......   (8)

Thus impulse is equal to the change in momentum.

The area under force - time graph and the time axis can also determine impulse of a force. From equation 8

Impulse =  

              = area ABC      ....... (9)

Let us discuss some application based on the concept of impulse.

We know that

Impulse = force x time = change in momentum

or    Force  =  change of momentum / time

In all the following applications force can be reduced by increasing the time of contact or time of impact.

a. While catching a cricket ball, a cricket player moves his hand backwards to increase the time duration of completing the catch. Thus, he exerts a lesser force to stop the ball and saves his hands from getting hurt.

b. Vehicles like cars, buses, scooters, trucks are provided with shockers to increase the time duration of the jerks. Hence, smaller force is exerted on the passengers on the vehicles during jerks.

c. Trains compartments are provided with buffers to increase the time duration of jerks during shunting.

d. A person falling on cemented floor is likely to get more injury than on falling on a sand floor because sand floor increases the time of duration of contact and hence, the force exerted by the sand floor is much smaller.