Impulse and Momentum

What’s the Big Idea‽

This lab explores the Impulse-Momentum Theorem and the relationship between impulse and momentum.

Procedure

On the technical side of things, we needed a Vernier LabQuest, a laptop, a motion detector, and a force probe. On the less technical side of things, we needed a dynamics cart, a frictionless track, a 500 g mass, some string, a rubber band, and a rod with its accompanying stand.

To set up, we placed the cart on the track, with the motion detector on one side and the force probe secured on the rod on the other side. The end of the cart was attached to a rubber band which was attached to the string which was attached to the force probe.

The basic setup. 

Another view of the setup.

After setting everything up, we measured the mass of the cart (which was 0.51 kg) and opened Logger Pro. We calibrated the force probe and began collecting data, pulling the cart away from the force probe and letting it bounce back. The combined use of the force probe and the motion detector allowed us to measure position, time, velocity, and force, as shown in this graph:

The measured data.

What’s fantastic about Logger Pro is that it allows us to easily calculate and visualize the impulse given to the cart by taking the integral of the curve.

Takeaways

From this lab, we learned that impulse is not only equal to the change in momentum, but the integral of force over time. Additionally, specifically regarding this experiment, a higher spring constant in the rubber band yields a greater change in momentum and therefore a greater impulse.