Lab #15: Collisions in two dimensions
Daniel Guzman
Physics 4A.
The purpose of this particular laboratory is to analyze a to dimensional collision and from it determine if the momentum and kinetic energy was conserved in the system.
Description of the apparatus: The apparatus for this particular experiment consisted of a glass board or a glass table, two metal marbles, a clamp and a cellphone. In this particular experiment the glad board or glass table was used so the collision between the two marbles could be recorded completely without the marbles falling out of the board or table after they collide. The two marbles in the experiment were the to objects that collide and obviously were the objects analyzed. The phone in this experiment was used as a camera due that some phones can record 120 frames per second, which makes the analysis of the physical phenomena easier.
This apparatus displays the glass board, the clamp and the two metal marbles used in the experiment.
Experimental procedure: The experimental procedure for this particular experiment consisted first on setting up the apparatus correctly, which was very simple, due that apparatus only consisted of the glass board, the two marbles and the clamp. Once the apparatus was set up just as it is displayed on the picture, one can proceed and run a trial to see if the camera has to be adjusted or not, once this is done one run the trials and records them. Once the recordings of the collisions have been made one can go ahead and upload the videos on to logger pro where the analytical part of the lab is carried out. When the videos are uploaded on to logger pro we used a tool that lets one picture the motion of each ball with respect to time from which we analyzed the collision of the balls. From the graphs of position vs time of the marbles we found out which were the initial and final velocities of each marble, and once one has the velocities one can proceed and verify if the momentum and the kinetic energy of the system is conserved.
This graph shows the position of the marbles in the two collisions recorded, also in this graph is shown the initial and final velocities of the marbles (which are going to be used to verify if the kinetic energy and momentum of the system was conserved). Using this particular feature of logger pro is very powerful because it allows one to model the motion of the marbles accurately, which facilitates the extraction of important data such as the velocity before the marbles collide and the final velocity of them.
Video of the collisions
Video of the collision between two marbles of the same mass
Video of the collision between two marbles of different mass
Data table and calculations
The data collected for this particular experiment is on red, The data collected was the masses and the velocities, the other values that appear on the table are calculated results
Same Mass (elastic collision)
Different Mass Data collected and calculations.
The data collected for this particular trial was the initial velocity the final velocity and the mass of the marbles, the other values on the table are calculated results for the initial and final momentum.
Calculations
The calculations made were to verify if the initial and final momentum was conserved before and after the collision of the marbles. Also these calculations were made to confirm if the initial kinetic energy would equal the final kinetic energy before and after the collision. The calculation for momentum had to be done for the x and y components due that momentum is a vector, yet for the kinetic energy the calculations were much easier due that one only has to compare the kinetic energy before the collision and the final kinetic energy after the collision.
Conclusion
After doing the calculations and interpreting the data collected in the experiment the kinetic energy and the momentum results before and and after the collision were different, which allows one to infer that there are multiple sources of error and uncertainty, for instance the mass of the marbles was not measured using the right balance, which definitely brings uncertainty and error to the calculations, the mass of the marbles should have been measured using an analytical balance that would read at least to the thousandths place, yet the one used only reads to the tenths place. another source of error in the experiment might come from not editing the video correctly due that if this is not done right the position of the marbles with respect to time before would not be the correct one due to wrong editing. The percent errors in this experiment were really high due to the sources of error mentioned before; for instance in the collision were both masses were the same the percent error was around 30 %. This percent error allow one to say that something in the experimental procedure or how the experiment was carried out was not done correctly.
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