Tuesday, June 9, 2015
Lab #20: Conservation of Energy and Angular Momentum
Purpose: Using the conservation of energy and momentum we will predict the height a system will swing up to after experienceing an inelastic collision.
Procedure: We set up C-clamps, bars, other clamps and a rotation sensor for our meterstick to rotate on. We also wrapped tape around the swinging end of the meter stick and tape around a small mass of clay that will stick to meter stick. The clay mass will be positioned directly where the meter stick will be at the bottom of its swing. We also set a small block of wood behind where the collision will take place as a marker.
This experiment will be broken up into three seperate parts for calculations:
Part 1 is the conservation of energy when we transfer our potential energy from our horizontal position to the kinetic energy the ruler will experience at the bottom of its swing.
Part 2 is the conservation of momentum of the swinging ruler having an inelastic collision with the mass of clay.
Part 3 is conservation of energy again but this time starting with the kinetic energy of the swinging system transfering into gravitational potential energy at its mas swing height.
One very important thing that we had to take account of during these calculations was that the center of mass of the ruler was not a perfect .5 meters away from the pivot. To adjust for this we used the parallel axis theorem for the shift whenever we calculated inertia of the meterstick. Likewise the mass of clay would not be a perfect 1m away from the pivot, but all we had to adjust for this was the distance we used because it is a point-mass.
Finally after our calculations we came up with a prediction for the max angle and height of the swing. Now we set up our camera and logger-pro to capture and analyze the experimental run.
We compared our theoretical value to what we collected in logger pro and calculated our percent error.
Our percent error was fairly small and possibly due to things like not releasing the meterstick from a perfectly horizontal position, the clay not beint a perfect point mass and the motion capture also distorting the data just a bit.
Overall it is fairly easy to show that both energy and momentum were conserved it this inelastic collision and in an entertaining way where we get to swing a meter-stick into a small mass.
Procedure: We set up C-clamps, bars, other clamps and a rotation sensor for our meterstick to rotate on. We also wrapped tape around the swinging end of the meter stick and tape around a small mass of clay that will stick to meter stick. The clay mass will be positioned directly where the meter stick will be at the bottom of its swing. We also set a small block of wood behind where the collision will take place as a marker.
This experiment will be broken up into three seperate parts for calculations:
Part 1 is the conservation of energy when we transfer our potential energy from our horizontal position to the kinetic energy the ruler will experience at the bottom of its swing.
Part 2 is the conservation of momentum of the swinging ruler having an inelastic collision with the mass of clay.
Part 3 is conservation of energy again but this time starting with the kinetic energy of the swinging system transfering into gravitational potential energy at its mas swing height.
One very important thing that we had to take account of during these calculations was that the center of mass of the ruler was not a perfect .5 meters away from the pivot. To adjust for this we used the parallel axis theorem for the shift whenever we calculated inertia of the meterstick. Likewise the mass of clay would not be a perfect 1m away from the pivot, but all we had to adjust for this was the distance we used because it is a point-mass.
Finally after our calculations we came up with a prediction for the max angle and height of the swing. Now we set up our camera and logger-pro to capture and analyze the experimental run.
We compared our theoretical value to what we collected in logger pro and calculated our percent error.
Our percent error was fairly small and possibly due to things like not releasing the meterstick from a perfectly horizontal position, the clay not beint a perfect point mass and the motion capture also distorting the data just a bit.
Overall it is fairly easy to show that both energy and momentum were conserved it this inelastic collision and in an entertaining way where we get to swing a meter-stick into a small mass.
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