Impulse and Momentum

What if the force changes over time?

In the same way we looked at the Work done by a varying force, we can make an approximation to the impulse or the change in momentum by adding up rectangles of width t and of height F.

And, again, just as we did for the work due to a varying force, we can make this "approximation" better by going to more rectangles, each of a smaller width or smaller time interval.

The end result, of course, is that

This change in momentum can be caused by a small force acting over a long time.

Or the same change in momentum can be caused by a large force acting over a short time.

Conservation of Momentum			Collisions
Return to ToC, Ch9, Linear Momentum

(c) Doug Davis, 2001; all rights reserved