Daniel Guzman
Physics 4A.
Magnetic Potential Energy Lab
The purpose of this experiment was to demonstrate that the energy in the system is is conserved at every single moment, in this particular experiment the purpose was to realize that the kinetic energy of the glider and the potential magnetic energy was conserved in the system.
Apparatus description
The apparatus used in this particular experiment consisted of an air track, which had a magnet attached to it, a glider that also had a magnet attached to one of its ends, a motion sensor, a laptop, and a cellphone to measure the different angles at which the glider was moving when approaching the magnet that was fixed in the air track.
Experimental Procedure
The experimental procedure of this particular experiment consisted on making different measurements for angles, distances and mass. The first measurements made by my lab group and I were measurements of distance, which were going to allow us to determine how far does the glider was going to be from the magnet that was put on the track, to come out with good accurate measurements we first measured the distance at which the magnet had been put on the track, so it would be easier to use the entire length of the track to make all the measurements desired. After we measured this first distance we measured the distance at which the glider would stop from the magnet. Once having these two measurements we would have a reference of the position of the glider and by having this reference we would only measure the distance at which the glider would stop. Once these measurements of position were made we proceeded and started to make measurements of the angles at which we would let the glider slide for it to approach the magnet on the track. once these measurements of the angle were made we had to use different objects to maintain the track at that precise inclination so the glider would move at a constant angle, right when the track was fixed we would turn on the air track and the glider would approach the magnet, which made the glider bounce back a certain distance, which we would measure and record, the distance measured was the distance using the entire length of the track, which was possible and easier due that we had already measured the distances described previously. Once this was measured and recorded, we proceeded and repeated the same process six more times in order to have enough data to plot a graph of the magnetic force and the separation distance. The data recorded was necessary to determine the magnetic force, which had to be graphed in order to determine a function that would describe the relationship between the magnets in terms of distance.
After the data was plotted and some calculations were made we proceeded to second part of the experiment which was to compare the kinetic energy of the cart and the potential energy of the system, to do this we used the motion sensor to determine the velocity of the glider at any point when it was moving and we set the function found as a parameter on the computer to be able to compare the graphs of the kinetic energy of the cart to the potential magnetic energy.
Measured data and calculated data
Measured data (red) and calculated data (blue)
Sample calculation for the magnetic force and derivation of the potential magnetic energy in terms of distance (r)
The magnetic force was calculated using the following equation Fmag= mgsin(theta), the angle theta changed for every trial.
To come up with the function of Potential energy in terms of distance, a plot of the magnetic force and the distance r had to be done. Once this plot is done one can obtain the values for A and b to then do the integration that will yield the function the function of potential energy in terms of distance (r).
Graphs
The values for this particular plot were the magnetic force calculated and the distance r measured .
This graph represents the relationship between magnetic force and the distance(r) between the magnet on the glider and the magnet on the track. As this graph shows, as the glider gets closer to the magnet. In this graph we used a power fit and obtained the values for A and B, which are really important because they are used when coming up with the equation of the potential energy in terms of r.
This is the most important graph of the experiment because it demonstrates that the total energy of the system is conserved thorough the experiment. For example, the potential energy increases to a maximum when the kinetic energy completely decreases, and vice-versa when the potential energy of the system decreases to zero there would only be kinetic on the system, this is observed on the graph when the potential energy in red decreases the kinetic energy of it increases.
Conclusion
This experiment was trying to show one that the energy on any system is conserved, in this particular experiment one was trying to demonstrate and realize that energy of the system was conserved, after collecting data and doing calculations we were able to show that the energy is conserved. Obtaining accurate results in this experiment was very amazing because it allows one to realize that energy was never lost, and that the total energy of the system was conserved every single moment. The goal of this experiment was accomplished because when one analyzes the graph one notices that when there's no potential energy in the system the energy in the system is all kinetic energy, and vice versa when there is not kinetic energy in the system all the energy is potential. The sources of uncertainty and error in this experiment might come from the measurements made, for instance measuring the angles or the distance were the glider would stop can bring some error, nevertheless the error obtained in these measurements was very small, this can be proven to the uncertainty values in the graph of magnetic force vs distance. Another source of error can come from making wrong assumptions about the system such as ignoring air friction and assuming that the track was perfectly friction-less, yet the error that comes from making these assumption is minimal because the air resistance and friction were minimal. The goal of the experiment was achieved due that one was able to obtained a graph that shows that the total energy of the system is conserved thorough the entire experiment
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