- "How can we store energy to do work for us later?"
- “How does the force it takes to stretch a rubber band depend on the AMOUNT by which you stretch it?”
- In this lab, we used a series of procedures using a rubber band and an electronic force probe to derive an equation for potential energy.
- First we stretched the rubber band a certain disrance andmeasured the force ittook to hold the rubber band in the stretched position. A picture of how this looked -->
- From the input of distance and output of force, we came up with a data table that looked like this <--
- The two trials were just for accuracy, and we tested the force needed to pull the rubber band when it had just one loop, and also a double loop.
- Then from this data, we graphed the points of the single loop data and drew a best fit line throught them. after finding the slop of our best fit line (77. 65 N/kg), we started to think of the components of our data and graph in terms of the equation of a line, y=mx+b. From this we derived Fs=kx9(+0)
- Since we know the area under a force vs. distance graph is always the energy, we plugged in the force needed to strength the rubber band, and distance stretched into the equation A=1/2b - h. From this, we derived E= 1/2x - Fs. (we were able to do this just by substituting what our graph was labeled, for what the generic area equation called for.) Because we know Us=1/2b - h, we can start plugging things in and we get our final equation which is Us= 1/2kx^2. These prodecures are shown below:
- Because of this data and these equations, we can define potential energy as stored energy that does work for us at a later time.
A Real World Connection
- This lab made me think about all the different things that store energy that release that energy at a later time. For instance, a bow and arrow. Once in place, you pull the arrow back. Once you release the force you were aplying, the arrow uses its energy and shoots forward.
No comments:
Post a Comment