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PHYSICS 183 for Fall 2009
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ENERGY I Part I: In this part of the lab, you will do some qualitative investigations of energy to practice with the concepts of kinetic and potential energy. There are no calculations in this part just thinking. Therefore, you need to write good descriptions of your thoughts in your notebook. Do not allow the cart to crash off the end of the track! Elevate the track so that the end without the bumper is higher than the other end. The cart has a spring in one end which can be compressed and held at three different positions. Compress the spring to the maximum possible and set the spring end of the cart against the bumper. Release the spring by tapping on the release mechanism. (Using the eraser end of a pencil or a ruler works better than using your hand. Be sure to press straight down so that you don’t give the cart an extra shove to the left or right.) Describe what happens. Set the angle of the track such that the cart travels more than half of the track for the greatest spring compression. Estimate the distance traveled to the highest point in the motion. Repeat the experiment with the other two compression distances. Explain your results in terms of energy. Now using the greatest compression available, try different amounts of mass on the cart. Describe what you observe. Again, explain your results in terms of energy. Experiment with the track set to different angles. What is the nature of the relationship between the angle of the track and the distance traveled? Explain your results in terms of energy. Part II: Set the sonic ranger near the raised end of the track. Using the cart without any extra mass and the greatest compression, make distance, velocity and acceleration graphs. Release the cart once you hear the sonic ranger start 'chirping'. Print your graphs and include them in your report. Think about your graphs in detail. Is the behavior of the graphs as you would have expected? Explain what is happening in each part of the three motion graphs. Why is the second acceleration peak greater in magnitude than the first one? Use Logger Pro™ to calculate the the kinetic energy, gravitational potential energy (getting the y in GPE takes a little thought), and total energy of the cart. Plot a graph of total energy versus time. Is the energy of the cart conserved? What evidence do you have to support your answer? If it is not conserved, where does the lost energy go? Describe any other interesting physics you noticed in this experiment that was not covered in answering the above questions.
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