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Unformatted text preview: Problem 1. (32 points) Answer the following questions and give brief explanations for your answers . Just stating the answer without explanation is not sufficient. Note, there are also questions on the back of this page. Answer all the parts! (a) You have a tennis ball in your hand and throw it straight down from a height h so that it bounces off the floor and returns to your hand at a height h , 1 . 0 s later. What is the average velocity of the tennis ball for this motion? (b) An automobile has an initial velocity v 1 and brakes to a stop in time t 1 with a constant deceleration a 1 . If the initial velocity is instead twice as large, v 2 = 2 v 1 , and the deceleration is half as large, a 2 = a 1 / 2, what is the ratio of stopping times between these two cases, t 2 /t 1 ? (c) The speedometer of your automobile shows that you are proceeding at a steady speed of 80 km / h for some time interval. Can your automobile be accelerating during this time interval? F m (d) You hold your physics book at rest against a rough wall by exerting a force F on the book. Draw a complete free-body diagram for the book. [ Note : There is friction between the book and the wall. Ignore friction between your hand and the book.] Wednesday, 14 February 2007 1 PHYS 121 Exam I Problem 1 continued: 3 2 1 y x (e) [8 points] Identical projectiles are launched that follow the three trajectories...
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This homework help was uploaded on 04/08/2008 for the course PHYS 121 taught by Professor Kernan during the Spring '08 term at Case Western.
- Spring '08