Conservation of Angular Momentum
Partners: Me, Myself, and I
Date: 3/18- 4/1
Date: 3/18- 4/1
Purpose
The purpose of this experiment is to prove the Law of Conservation of Angular Momentum.
Theory
The Law of Conservation of Angular Momentum states that the initial and final angular momentum are equal and that if no net torque acts on an object then there is no change in angular momentum. If net torque is zero then angular momentum is constant or conserved.
Below is the equation for the Moment of Inertia for the disk.
Below is the equation for the Moment of Inertia for the disk.
Below is the equation for the Moment of Inertia of a ring. The two r's represent the inner and outer radii.
Below is the equation to find both the initial and final angular momentum. The equations equal each other since the Law of Conservation of Angular Momentum states that the initial and final momentum are equal. L3 is crossed out on the initial side because that represents the ring and since it is not added to the system it is zero. The Moment of Inertia for both disks and the ring are substituted for I and anything that can be brought out of the parenthesis.
Experimental Technique
Apparatus
-Rotary Motion Sensor -Two Disks -Ring -Stand -Digital Adaptor -Notecard -Tape -Computer -DataStudios -MicroSoft Excel -Calculator -Vernier Caliper |
Procedure
1. Attach the rotary motion sensor to the stand. 2. Attach the two disks to the pulley and line them up. 3. Set the ring down on the notecard and trace the outer edge. 4. Cut out the circle and tape it to the ring. 5. Put a hole in the center of the notecard. 6. Set up DataStudios and MicroSoft Excel. 7. Hit the Start button on DataStudios 8. Spin the two disks (without the ring on top). 9. Drop the ring on to the center using the hole in the notecard as a guide. 10. Stop the recording. 11. Record the average initial and final velocity. 12. Conduct a total of ten trials and record them onto MicroSoft Excel. 13. Calculate the initial and final angular momentum. 14. Calculate percent difference between initial and final angular momentum. |
Data
Analysis
Conclusion
The experiment went better than hoped. This lab was chosen because the equipment for the other experiment was taken so I was stuck with this one. It also seemed easier than the other. The only problem I encountered was that the angular momentums did not always equal each other. If I were to redo the experiment I would try to find a way to make the whole apparatus more stable.
There are three possible reasons as to why the initial and final angular momentum were not equal. The drop is one possible reason because if it is not dropped straight it can throw off the distribution of mass. It was resolved as much as possible with the notecard. The rotary motion sensor is another possible reason because it wobbled when spun at high speeds. The stand also wobbled a lot. One possible way to fix those problems was to slow down the angular velocity.
There are three possible reasons as to why the initial and final angular momentum were not equal. The drop is one possible reason because if it is not dropped straight it can throw off the distribution of mass. It was resolved as much as possible with the notecard. The rotary motion sensor is another possible reason because it wobbled when spun at high speeds. The stand also wobbled a lot. One possible way to fix those problems was to slow down the angular velocity.
References
Boundless. (2014, July 3). Conservation of Angular Momentum - Boundless Open Textbook. Retrieved April 2, 2015, from https://www.boundless.com/physics/textbooks/boundless-physics-textbook/rotational-kinematics-angular-momentum-and-energy-9/conservation-of-angular-momentum-86/conservation-of-angular-momentum-328-11269/