Impulse and Momentum

Introduction

The impulse-momentum theorem relates impulse, the average force applied to an object times the length of time the force is applied, and the change in momentum of the object:

Here we will only consider motion and forces along a single line. The average force, F, is the net force on the object, but in the case where one force dominates all others it is sufficient to use only the large force in calculations and analysis.

For this experiment, a dynamics cart will roll along a level track. Its momentum will change as it reaches the end of an initially slack elastic tether cord, much like a horizontal bungee jump. The tether will stretch and apply an increasing force until the cart stops. The cart then changes direction and the tether will soon go slack. The force applied by the cord is measured by a Force Sensor. The cart velocity throughout the motion is measured with a Motion Detector. Using Logger Pro to find the average force during a time interval, you can test the impulse-momentum theorem.

Objectives

• Measure a cart's momentum change and compare to the impulse it receives.
• Compare average and peak forces in impulses.