Impulse


 
 
Concept Explanation
 

Impulse

It is termed as the total impact of force. This is equal to the change in momentum of the body. In other words, impulse is defined as the product of force and a small time in which the force acts.

SI unit of Impulse if N s (Newton Second) or kgm/s.

Impulse Equation: 

Impulse is often stated to be the product of the average net force that acts on an object for a ceratin duration.The equation for impulse is given as;

J:=:FDelta t

Note : We assume that force is constant over time.

Impulse is a vector quantity like force and it also has direction.

Impulse - Momentum Theorem

The Impulse-Momentum theorem helps us establish the relation between the two concepts. The theorem basically states that the change that is seen in the momentum of an object is equivalent to the amount of impulse exerted on it.

Basically, you should understand that impulse is a measure of how much the momentum changes. Here we also get an alternative formula which is given as;

underset{j:=:}{rightarrow}underset{::;p_2::-}{rightarrow}underset{p_1}{rightarrow}

Where  p_1:=: initial momentum,   p_2:=:  final momentum  

With this formula,we can further clearly relate impulse to the chnges in the momentum of the object.

Q.A 650 - kilogram rocket is to be speed up from 440 meters per second to 520 meters per second in outer space. If the thrust of the engine is 1200 newtons, for how long must the engine be fired?

Solution: The change in the momentum of the rocket    Delta P:=:mv:-:mu

                 =  (650)(520) - (650)(440) = 52000 kg m/s.

This must be equal to the impulse, so FDelta t   =  (1200N)(t)  =  52000 kg m/s

Therefore ,  Delta t  =  43 s

Sample Questions
(More Questions for each concept available in Login)
Question : 1

Due to an impulse, the  change in momentum of a body is  1.8;kg m s ^-^1. If the duration of the impulse is 0.2 s, then what is the force produced in it ?

Right Option : A
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Explanation
Question : 2

A stationary ball weighing 0.25 kg acquires a speed of 10 m/s when hit by a hockey stick. The impulse imparted to the ball is _____________

Right Option : A
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Explanation
Question : 3

kg ms^-^1 is the SI unit of   _____________________-

Right Option : A
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Explanation
 
 
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