Calculating Force and Time with Impulse: When and How?

[mahela007]

In what kind of instances would the quantity of impulse be used? My textbook says that it's when very large forces act for very short times but how would that help us calculate the force OR the time?

 

[Shooting Star]

It is precisely when we cannot or do not need to calculate the force or the time for which it acts that we use the concept of impulse. The impulse is the integral of the force with respect to time and can be proved to be equal to the change in momentum. Here are some good sites for preliminary reading:

http://id.mind.net/~zona/mstm/physics/mechanics/momentum/introductoryProblems/momentumSummary2.html
http://www.glenbrook.k12.il.us/gbssci/phys/Class/momentum/u4l1b.html

 

[arildno]

A classical example is in the analysis of collisions.

 

[jtbell]

When I was in school, I was "into" model rocketry for a while. Solid-fuel model rocket engines were rated in terms of the total impulse they produced, between ignition and burnout. The actual thrust (force) exerted varied widely during the burn period, but the burn period was short enough that you could use the total impuse to calculate good estimates of launch speed, maximum height of trajectory, etc.

 

[mahela007]

Thanks