A force which acts for a very short time but produces an appreciable change of momentum is called impulsive force .
Impulse is defined as the total change in momentum produced by the impulsive force.
or
Impulse is defined as the measure of large force on a body for a very small duration.In some cases the force acting on a body is not constant or it acts for a very short time.For example,when a collision takes place between two bodies or when a blow is made.With a hammer,it is ordinarily not possible to measure the actual value of the force as its value changes with time.In such cases the effect of the force is measured by the total change in momentum that it produces in a given time.
If the velocity of a body of mass m change from u to v in t second,then the total change in momentum during this time is (mv-mu).If F is the average force applied,then
F = mv-mu/t = p2-p1/t = rate of change of momentum {Newton's 2nd law}
or Ft = p2-p1= total change in momentum
Thus,impulse may be defined as the product of force and time and is equal to the total change in momentum of the body.
Application of impulse
1. A cricket player while taking catch of fast moving ball lowers his hands to avoid injury.Because by lowering his hands time of catch is increased so that less force is required to stop the ball,and ball also exerts lesser force on the hands of the player.
2.Shockers are in vehicles such as scooters,car,motorcycles etc.to save the passenger from jurks because the shockers used in vehicles increase the time of impulse and hence the impact of jurk on the passenger is reduced.
3.Glassware,chinaware and other delicate objects are wrapped in straw or paper before packing to save them from breakage.
4.Buffers are provided between two bogies of a train to avoid severe jerks on the passengers.
5.A person falling from certain height on cemented floor receives more injury than a person falling on a heap of sand.
6.A person while jumping from a wall folds his legs to avoid injury.
7.The head-on collision of vehicles causes more damage as time of impact is very small hence much more force is developed which causes damage to vehicles.
8. Electronic equipments are packaged with the help of thermocol or sponge to save from damage caused by jerks.
Impulse is defined as the total change in momentum produced by the impulsive force.
or
Impulse is defined as the measure of large force on a body for a very small duration.In some cases the force acting on a body is not constant or it acts for a very short time.For example,when a collision takes place between two bodies or when a blow is made.With a hammer,it is ordinarily not possible to measure the actual value of the force as its value changes with time.In such cases the effect of the force is measured by the total change in momentum that it produces in a given time.
If the velocity of a body of mass m change from u to v in t second,then the total change in momentum during this time is (mv-mu).If F is the average force applied,then
F = mv-mu/t = p2-p1/t = rate of change of momentum {Newton's 2nd law}
or Ft = p2-p1= total change in momentum
Thus,impulse may be defined as the product of force and time and is equal to the total change in momentum of the body.
Application of impulse
1. A cricket player while taking catch of fast moving ball lowers his hands to avoid injury.Because by lowering his hands time of catch is increased so that less force is required to stop the ball,and ball also exerts lesser force on the hands of the player.
2.Shockers are in vehicles such as scooters,car,motorcycles etc.to save the passenger from jurks because the shockers used in vehicles increase the time of impulse and hence the impact of jurk on the passenger is reduced.
3.Glassware,chinaware and other delicate objects are wrapped in straw or paper before packing to save them from breakage.
4.Buffers are provided between two bogies of a train to avoid severe jerks on the passengers.
5.A person falling from certain height on cemented floor receives more injury than a person falling on a heap of sand.
6.A person while jumping from a wall folds his legs to avoid injury.
7.The head-on collision of vehicles causes more damage as time of impact is very small hence much more force is developed which causes damage to vehicles.
8. Electronic equipments are packaged with the help of thermocol or sponge to save from damage caused by jerks.