November 24, 2009
Today in class we has a QOD, and started a new lab called the Impulse Lab.
Here is the link to the QOD.
In this QOD the first part asked us to find the change in momentum. Since the bowling ball was 6kg and its velocity was 2m/s, you just have to multiply them together. The equation looks like this equation10.png. The next part asked us to find the impulse on the bowling ball. In the QOD there is a graph shown at the right. It had a box that we needed to find the area of. The length of the box, or the Fnet was -5N and the change in time, or the width, was 1sec. To find the impulse all we had to do was multiply these two numbers together. The equation for impulse looks like this equation11.png. The final part of the QOD was extra credit. It was asking us to find the post-collision momentum of the bowling ball. To find this, all we had to do was subtract the fist change in momentum minus the impulse.

For the Impulse Lab, our goal was the prove the equation for the change in momentum-the force multiplied by the change in time is equal to the mass multiplied by the change in velocity, (equation.png) We all know this is true but we need to prove it is in this lab. Our materials used in this lab were a cart, a stretchy string, a force probe, 1 kg mass, and a motion detector with LoggerPro. What we were trying to do was record the motion of a cart with a feel of 9.8 N (1 kg mass for the force of gravity with the force probe), while attached to a stretchy string. In terms of the motion, the cart would have momentum towards the detector, but being attached to a string it will slow down and rapidly bounce back with momentum in the opposite direction. As we detected this motion we had 2 graphs show us the force with time, and the velocity with time. In order to prove the equation to be true, we need to find the area of the force vs. time graph and find the change in velocity from the velocity vs. time graph. Today was day 1 of a 2 day lab, having this lab is due Monday, November 30.