PY105_2005_Test1

# PY105_2005_Test1 - PY105 Test 1, Fall 2005 PROBLEM 1 10...

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PY105 Test 1, Fall 2005 PROBLEM 1 – 10 points The graph shows your motion along a straight sidewalk over a 50-second interval. [2 points] (a) What is your velocity at t = 45 s? [2 points] (b) What is your acceleration at t = 10 s? [2 points] (c) At which of the following four times do you have the lowest speed? [ ] at t = 5 s [ ] at t = 15 s [ ] at t = 25 s [ ] at t = 35 s [2 points] (d) What is your average velocity over the 50-second interval? [2 points] (e) What is your average speed over the 50-second interval?

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PROBLEM 2 – 10 points While riding in a gigantic elevator, you decide to kick a hockey puck around for fun. The coefficient of static friction between the hockey puck and the floor of the elevator is μ s , while the coefficient of kinetic friction is μ k . The mass of the hockey puck is m. Express your answers in terms of the variables given in the problem and/or g. [5 points] (a) The elevator starts out at rest on the first floor, and accelerates upward at a constant rate a. While the elevator is accelerating, you kick the puck horizontall y. What is the minimum force that you must apply in order to get the puck moving horizontally? In order to receive full credit, you must draw a clear free body diagram and show all work. [5 points] (b) The elevator reaches its constant cruising speed v. What is the minimum force that you must apply (horizontally, as before) in order to the get the puck moving horizontally? In order to receive full credit, you must draw a clear free body diagram and show all work.
PROBLEM 3 – 10 points A beer mug full of beer slides across a horizontal bar, starting out with initial velocity v 0 . The coefficient of static friction between the mug and the bar is μ s , while the coefficient of kinetic friction is μ k . The mass of the mug is M, and the amount of beer contained in the mug is m.

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## This note was uploaded on 04/17/2008 for the course PHYSICS 105 taught by Professor Duffy during the Fall '06 term at BU.

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PY105_2005_Test1 - PY105 Test 1, Fall 2005 PROBLEM 1 10...

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