lab 19: conservation of energy and conservation of angular momentum ( Daniel Guzman) lab partners James okamura and Rodrigo uribe

Daniel Guzman
Physics 4A
Conservation of energy and angular momentum


The purpose of this lab is to use the principles of angular momentum and conservation of energy to find how high a stick can go after colliding with a piece of clay that is at rest on the ground

The theory used in this experiment and particular lab is very important due that it uses two fundamental principles such as conservation of angular momentum and conservation of energy. Both of these two principles are used to find how high the clay and the stick would go; for instance, the principle of conservation of energy is used to find the angular velocity at which the stick would hit the clay that is at rest, the principle of conservation of energy is used due that the ruler is at rest is initially. after being displaced from its natural position which means that it has gained gravitational potential energy and it would be conserved in the from of kinetic energy. after the stick hits the clay and they become one body due that they stick together, we apply conservation of angular momentum, this principle can be used due that not other torque is acting on the system, which means that the momentum is conserved, using this principle we can use the initial angular velocity of the stick before hitting the clay to find the angular velocity once it hits the clay and the clay sticks to the ruler. Once again we used the principle of conservation of energy to find how high the stick would go with the clay.

Description of the apparatus
The apparatus for this experiment was quite simple it only consisted of a laptop, a meter stick, a piece of clay, a cell phone and a piece of clay. The laptop in this experiment is used to do a video analysis to determine how high the meter stick would travel with the clay. The cellphone is used to record the physical phenomena which is the piece of clay and meter stick sticking together.

The experimental procedure for this lab was the easiest from all the labs performed in this semester, due that one only needed a clamp to attached the meter stick and a bearing that would allow the meter stick rotate. After that was done one had to release the meter stick and record the collision the of the meter stick and the clay. After the video was analyzed we proceeded and apply the concepts described above to make some theoretical calculation about how high would the meter stick go.

Applying the theory described to find the maximum height that the stick travels (conservation of momentum and conservation energy used).

Comparing the theoretical results to the experimental results the percent error came up to be 14.5 %, which lets one infer that are multiple sources of error in this particular experiment or wrong assumptions were made in this experiment; for instance the pivot on which the stick is rotating is not friction-less, which we assumed it was. Another wrong assumption for this particular experiment was to assume that the mass was evenly distributed on the meter stick, which it was not because tape was added to the meter stick, which is going to change the moment of inertia and center of mass of the meter stick.

These two images let one compare the initial initial and final positions of the stick and from this graphs were would be able to compare the experimental and theoretical results

This image shows the final position of the stick from which we calculated the percent error of the experiment using the theoretical results calculated.

Conclusion: The data and results obtained for this experiment were not very accurate due that the percent error was 14.5 percent, which means that different sources of error affected the experiment. When comparing the theoretical and experimental results they were not close enough, which lets one assume that the experiment was not very accurate, and there were multiple sources of error.