Lab 19: Conservation of Energy/Conservation of Angular Momentum
May Soe Moe
Lab Partners: Ben Chen, Steven Castro, Stephanie Flores
Date: 31-May-2017
Objective: To determine how high the clay-stick combination rises after the collision, and compare the experimental results with theoretical results
Introduction:
In this lab, we will theoretically figure out how high the clay and the stick rises up after the meter stick collides with the clay by using the conservation of angular momentum and the conservation of energy. We will use the conservation of energy first to find out the angular velocity of the stick right after the collision. Once we get the initial angular velocity, we will use the conservation of the angular momentum to find out the final angular momentum. After that, we will use the conservation of energy again to get the maximum height the clay and the meter stick reach after the collision. Experimentally, after setting up the apparatus, we will shoot a slow-motion video with an iPhone of the meter stick colliding with the clay and reaching up to the maximum height. After that, we will use Logger Pro to set up the initial point and final height of the clay and the meter stick. Logger Pro will give us the maximum height the clay and the stick reach together. We will compare what Logger Pro gives us with the theoretical calculation we did.
Experimental Procedure:
(1) We set up our apparatus as below:
(2) The pivot is at 10 cm mark, and we will consider the pivot is at 0 cm mark, the center of mass is at 40 cm mark, and the clay is at 90 cm mark.
(3) After setting up, we aim where to put the clay, so that the stick collides with the clay.
(4) We put the pins into the clay so that it would stand. The clay only sticks to the meter stick if it is standing on the pins.
(5) Once we got our aim, we set up a ring stand where the phone could capture the whole process of the stick colliding to the clay and the clay sticking to the stick.
(6) We made sure that we could see the maximum height the clay and the stick reached in the video.
(7) After recording the whole process, we inserted the video into Logger Pro.
(8) We define our x and y- axes and marked where the initial and final position of the stick. Logger Pro automatically determined the maximum height the clay and the stick reached.
Experimental Data:
One thing to note in this screenshot is that our actual maximum height is -0.3743, not 0.6104. We set our x and y- coordinates wrong, therefore, it is switched.
Theoretical Calculations:
Conclusion:
When we compared it to our theoretical maximum height (0.394m) and experimental maximum height (0.3743m), it has 5% difference and 5% percentage error. This is within acceptable range. The source of uncertainties might be that when we marked the clay to determine the maximum height in Logger Pro, it might not have been the same exact location on the clay, which could be a difference from the video. Overall, the lab was successful that our theoretical and experimental maximum height of the clay and the meter stick are close to each other. Therefore, we can also see that this experiment confirms the conservation of angular momentum and the conservation of energy.
May Soe Moe
Lab Partners: Ben Chen, Steven Castro, Stephanie Flores
Date: 31-May-2017
Objective: To determine how high the clay-stick combination rises after the collision, and compare the experimental results with theoretical results
Introduction:
In this lab, we will theoretically figure out how high the clay and the stick rises up after the meter stick collides with the clay by using the conservation of angular momentum and the conservation of energy. We will use the conservation of energy first to find out the angular velocity of the stick right after the collision. Once we get the initial angular velocity, we will use the conservation of the angular momentum to find out the final angular momentum. After that, we will use the conservation of energy again to get the maximum height the clay and the meter stick reach after the collision. Experimentally, after setting up the apparatus, we will shoot a slow-motion video with an iPhone of the meter stick colliding with the clay and reaching up to the maximum height. After that, we will use Logger Pro to set up the initial point and final height of the clay and the meter stick. Logger Pro will give us the maximum height the clay and the stick reach together. We will compare what Logger Pro gives us with the theoretical calculation we did.
Experimental Procedure:
(1) We set up our apparatus as below:
 |
| Our apparatus set up |
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| After the clay collides with the stick |
(3) After setting up, we aim where to put the clay, so that the stick collides with the clay.
(4) We put the pins into the clay so that it would stand. The clay only sticks to the meter stick if it is standing on the pins.
(5) Once we got our aim, we set up a ring stand where the phone could capture the whole process of the stick colliding to the clay and the clay sticking to the stick.
(6) We made sure that we could see the maximum height the clay and the stick reached in the video.
(7) After recording the whole process, we inserted the video into Logger Pro.
(8) We define our x and y- axes and marked where the initial and final position of the stick. Logger Pro automatically determined the maximum height the clay and the stick reached.
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| What we did in Logger Pro to get the maximum height |
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| We got the maximum height as 0.3743, experimentally. |
Theoretical Calculations:
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| Calculating the angular velocity at the bottom to find the angular velocity at maximum height |
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| Calculating angular velocity at maximum height and using it to find the maximum height |
When we compared it to our theoretical maximum height (0.394m) and experimental maximum height (0.3743m), it has 5% difference and 5% percentage error. This is within acceptable range. The source of uncertainties might be that when we marked the clay to determine the maximum height in Logger Pro, it might not have been the same exact location on the clay, which could be a difference from the video. Overall, the lab was successful that our theoretical and experimental maximum height of the clay and the meter stick are close to each other. Therefore, we can also see that this experiment confirms the conservation of angular momentum and the conservation of energy.
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