Elastic Collisions Experiment

In the video I show the set up I used for the Elastic Collisions Experiment. I had great success and was able to create collisions into immovable objects with only a 1.3% ±0.13% loss of speed. This measurement was found by taking the velocity of the cart before the collision and after the collision, using a photo gate. In the trial the cart would pass through a photo gate, collide with the immovable object and return through the photo gate where its velocity could again be measured. Over the 10 trials (all of the measurements are averages from 10 trials) I ran, the cart would return with 98.7% ±0.13% of the velocity it had before the collision. This was shocking to me.

Next, I ran the experiment with two carts of equal mass, using two photo gates, one to find the velocity of the first cart before the collision and the other to find the velocity of the second cart after the collision. The results were 98.3% ±0.27% of the first cart's speed was transferred to the second.

The next experiment I did was to test the equation of elastic collisions. To do this I made one cart half the mass of the other. I then collided the big cart into the small cart; I calculated the final velocities based on the initial velocity of the first cart. I found that the velocity of cart_1 after the collision was 14% ±3.2% off the calculated values, however this did not surprise me much because the velocity of the cart was greatly reduced and trying to get an accurate reading was difficult. The number that impressed me was the final velocity of cart_2, the calculated velocity is within 2.4% ±0.19% of the measured final velocity.

For the last run, I switched carts so the starting velocity of the big cart was zero and the small cart was being launched at it. This was the best data set I got all day. The results for the measured final velocity vs. the calculated final velocity were 6.3% ±0.89% and the results for the final measured velocity vs. calculated for cart_2 was 0.7% ±0.16%.

Over all this lab was a lot of fun and I was astonished by how close to the calculated final velocity it was possible to get. Playing with something with almost no friction was mind-bending, the carts would bounce off each other for what seemed like forever.

-Kyle