PHY214 Conservation of Momentum Lab Report PDF

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This is the PHY214 lab report regarding the conservation of momentum. This is for the fall 2020 course with James Buchholz....

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Running Header: CONSERVATION OF MOMENTUM

Lab #8: Conservation of Momentum Paige Hutton Lab Partner: Xavier Castaneda PHY214L-D October 14th, 2020 California Baptist University

Hutton 1

Hutton 2 Purpose: The purpose of this experiment is to investigate the law of conservation of momentum. In essence, the law of conservation is described as the “quantity of motion” of an object or a system of objects. When the net force outside of the system acting upon it is zero, the total momentum of the system remains constant. Therefore, the momentum of the system is conserved, in which the only exclusion to this would be if masses were changed. Zero net force is indicative of momentum being conserved. This lab applies to all three laws of motion, specifically Newton’s third law, which is that every force occurs as one member of an action/reaction pair of forces. Although it is extremely difficult to replicate a net zero force, we will attempt to recreate the effects of conservation of momentum.

Results: Mass of Glider (m₁) 190g 190g 190g 190g 190g 190g 190g 201g (needle) 201g (needle) ΔK 0.9614 -0.4797 -0.1938 -0.5378 -0.2384 -0.6303 14.75 -3.313 -2.309

V i of m₁ (m/s) 0.2175 0 0.2422 0 0.2490 0 -0.4687 0.2376 0

Mass of Glider (m₂) 211g 211g 251g 251g 311g 311g 211g 200g (wax) 200g (wax) Pi 0.4133 0.4146 0.4602 0.4824 0.4731 0.8080 0.0880 0.4776 0.5090

V i of m₂ (m/s) 0 0.1965 0 0.1922 0 0.2598 0.4638 0 0.2545

Pf 0.4798 0.3696 0.5781 0.3946 0.5338 0.7618 0.0321 0.4344 0.5778

V f of m₁ (m/s) 0 0.1945 -0.0269 0.2077 -0.0289 0.3152 0.4660 0.1024 0.1390 ΔP 0.0665 -0.450 0.1179 -0.0878 0.0607 -0.0462 -0.0559 -0.0432 0.0688

V f of m₂ (m/s) 0.2274 0 0.2057 0 0.1893 0.0524 -0.4044 0.1143 0.1492 % Error 16.09% 108.5% 25.62% 18.20% 12.83% 5.718% 63.52% 9.045% 13.52%

The calculations in the charts provided were determined with the following equations: 1 1 ∆ K =( v f2 − v i2) or 2 2

∆ K =K f −K i

P=mv ∆ P=P f −P i

Hutton 3 Questions: 1. If the glider were to collide with the end of the air track and rebound, momentum would not be conserved. The reasoning behind this is that the energy in that collision was a part of an action/reaction pair, as stated in Newton’s third law. The energy or force that the glider put into the air track is equivalent to the energy or force that the air track put back into the glider. Therefore, the momentum would be implicated due to the external force causing the net force to no longer be zero. However, after rereading the question, it is noted that the glider did not change speed at all, which may be indicative that the glider conserved momentum. Ultimately, it may be dependent on what the end of the air track is, whether it has a rubber band bumper or just a solid post. 2. It would appear that momentum was not conserved in our experiment due to the fact that we had large percent error results and the net external force was not zero. Although it is claimed to be impossible to recreate an external net force of zero in a lab, our results were a bit further from zero than desired. It would appear that our best conservations of momentum were during run 6, which was an elastic collision, and run 8, which was an inelastic collision with the needle and wax. 3. Unfortunately, there were no clear trends present in our data. It would appear that all of the runs excluding 6 and 7 were around the same area for initial momentum, but the range became skewed for the final momentum, allowing for marginal errors in our percent error. Some errors that may have been encountered were not waiting long enough for the glider to pass back through another photogate. Sometimes the glider was going so slow that it didn’t seem that it would reach the photogate yet again, so we cut the run short. It’s possible that even that very small velocity value would have corrected parts of our data. When we were running the trials, it seemed that everything was running smoothly, but according to our data, the first two runs were terrible and progressively got better for the most part. 4. The collisions for runs #1-7 were elastic in that the glider with initial velocity came to rest after hitting the second glider that was initially at rest. For these runs, there were only a few that actually caused the initially moving glider to rebound off of the initially resting glider. If the runs were inelastic, such as seen in runs #8-9 with the wax and needle attachments, the two gliders would have stuck together and continued moving with a common final velocity. When using the wax and needle, the needle stuck directly into the wax, causing the two gliders to stick together and then move off with the same final velocity. 5. If the air track had been tilted during the experiment, we could not accurately measure momentum being conserved in the collisions. In order for momentum to be conserved, there needs to be an external net force of zero, but the incline of the tilted track would make the external net force greater than zero. The velocities would be higher than when we had them levelled, but this would most likely cause for greater error. Conclusion: While doing the experiment, the results seemed fairly successful and simple. However, upon calculation and further analysis, it appears that only a few runs out of the nine total trials were mostly accurate, at best. It would appear that we drastically failed at conserving

Hutton 4 momentum in that the net force was never zero, which is typical for a lab but our results were a bit further from zero than desired. Some of the runs, such as runs 6 and 8 showed low percent errors, which would indicate that these are our most accurate runs of conserving momentum. Overall, the experiment was a good demonstration to understand the momentum of conservation, but our data shows that we were unable to recreate Newton’s fist law of motion for momentum....