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Unformatted text preview: Overton, Mays – Homework 3 – Due: Jan 28 2005, 4:00 am – Inst: Turner 1 This printout should have 13 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 2) 10 points The velocity v ( t ) of some particle is plotted as a function of time on the graph below. The scale on the horizontal axis is 8 s per grid square and on the vertical axis 8 m / s per grid square. 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 v ( t ) time × (8 s) velocity × (8m / s) Initially, at t = 0 the particle is at x = 62 m. What is the position x of the particle at time t = 32 s? Correct answer: 702 m. Explanation: Looking at the v ( t ) plot we see that over time t = 4 × 8 s = 32 s, the particle’s velocity decreases from the initial v = 4 × 8 m / s = 32 m / s to final v f = 1 × 8 m / s = 8 m / s. The v ( t ) line is straight, which indicates constant deceleration rate, hence the average velocity is given by ¯ v = v + v f 2 = 20 m / s . Consequently, the particle’s displacement during this time is simply Δ x = t × ¯ v = 640 m , and its final position x = x + Δ x = 702 m . 002 (part 2 of 2) 10 points What is the particle’s acceleration? Correct answer: . 75 m / s 2 . Explanation: The average acceleration of the particle is ¯ a = Δ v Δ t = v f v t = . 75 m / s 2 . Since the v ( t ) line is straight, the acceleration is constant, hence a = ¯ a = . 75 m / s 2 . 003 (part 1 of 1) 10 points A car traveling in a straight line has a velocity of 6 . 62 m / s at some instant. After 7 . 65 s, its velocity is 12 . 4 m / s. What is its average acceleration in this time interval? Correct answer: 0 . 755556 m / s 2 . Explanation: The average acceleration is a av = Δ v Δ t = v f v i Δ t = 12 . 4 m / s 6 . 62 m / s 7 . 65 s = 0 . 755556 m / s 2 004 (part 1 of 1) 10 points Vectors ~ A , ~ B , and ~ C are shown in the figure below. For convenience, the tails of each vector are arbitrarily located at (0,0)....
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This note was uploaded on 03/22/2008 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas.
 Spring '08
 Turner
 Physics, Work

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