18 November 2014: Angular Collisions Lab 18

Objective:
The purpose of this lab is to use knowledge about angular momentum and conservation of energy to find the height to which a ruler will rise when it collides with a stationary lump of clay.

Set up:

This is the set up for our lab. We used rods and clamps to be able to hang a ruler so that it rotates freely around a screw. The ruler would later be raised and it would hit the stationary lump of clay that was placed atop of rod.












Procedure and Results:
The first thing to do was to gather data about the setup and system. Firstly, it was important to note that the screw is not at the end but at the 0.02 mark. Also, the mass of the ruler 0.087 kg and the mass of the clay 0.028 kg. Being that we're using a meter stick, the length of the stick 1 m.

Next we decided to run first predict the height to which the meter stick would rise. Calculations can be seen below:

As you can see from our calculations, we predicted that the ruler would rise 0.303 m.

We then decided to test the validity of our prediction. We mounted a camera in front of the meter stick and a dark board behind the meter stick so that the clay would be more visible. We then raised the meter stick and let it go. It hit the clay and rose to some height. We captured the whole event on video and later analyzed the video.

We set coordinates on the video so that we would be able to find distances and velocities from the video. From the video, a table of values was created from which we made a graph:

As the table shows, the highest the meter stick ever rose was 0.233 m and from the graph we can see that as the ruler gained distance in the negative x direction, it also gained height, which can be expected from its rotational motion.

Conclusion:

Our prediction for the height that the ruler would reach is much higher than the height it actually reached. When we calculate percent error, we find that we have 23% error. Unfortunately we think that most of error came from the video analyzing. As you can see from the picture, the video came out blurry which made it hard to pin point exactly where the clay was at every frame. Also, we mounted the camera at the bottom which distorted our view of the system and hence the coordinates we placed upon our video. Had we mounted the camera higher perhaps our coordinates would have been more accurate.