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Unformatted text preview: Physics 1AL Testi ng a Model for Friction Summer Session II 2010 1 Introduction The study of physics is an attempt to make sense of the measurements we make. In these labs so far, you have made measurements of distance, speed, acceleration, and you have used theories to interpret and understand your data. A theory is just a model of nature, a model helping you to understand your measurements. Your model should be able to explain all the data available and it should allow you to make testable predictions about different situations. If you then go and make new measurements and find that they do not agree with the model that you used, then the theory must be changed or replaced by another. For example, it has been shown that Newton’s Laws do not agree with observations of objects moving near the speed of light. Einstein’s theory of relativity explains these new data. It turns out that the differences between relativity and Newton’s Laws are very small at lower speeds, so we can continue to use Newton’s Laws for our everyday lives, including almost all of Physics 1. (Even if your particle is moving at one tenth of the speed of light [that is a speed of 3x10 7 m/s = 6.7x10 7 mph] the difference between Newtonian mechanics and relativity is just a half of one percent. At half the speed of light the difference is 15 %.) But not all of the “theories” presented to you in a physics class are as simple, elegant, and well established as Einstein’s relativity or its subset - Newton’s Laws. One of these is the way introductory physics text books treat frictional forces. In this lab you will be able to measure how friction forces behave in a variety of situations. You will be able to test the assertions made in Chapter 4 of Serway and Faughn (bottom of page 99) against your own data. Before you start, read the section of your textbook (Ch 4.6) that covers frictional forces and how they behave. You should use the model of friction presented in the text book to answer the pre-lab questions....
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This note was uploaded on 09/25/2010 for the course PHYSICS 1A 1al taught by Professor Rafaelski during the Summer '10 term at UCSD.
- Summer '10