hw2_solns

hw2_solns - Answer, Key Homework 2 David McIntyre 45123 Mar...

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Answer, Key – Homework 2 – David McIntyre – 45123 – Mar 25, 2004 1 This print-out should have 15 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore making your selection. The due time is Central time. Chapter 2 problems. 001 (part 1 oF 1) 0 points The graph below shows the velocity v as a Function oF time t For an object moving in a straight line. t O v Which oF the Following graphs shows the corresponding displacement x as a Function oF time t For the same time interval? 1. t O x 2. t O x 3. t O x 4. t O x correct 5. t O x Explanation: The displacement is the integral oF the ve- locity with respect to time ~x = Z ~v dt . Because the velocity increases linearly From zero at frst, then remains constant, then de- creases linearly to zero, the displacement will increase at frst proportional to time squared, then increase linearly, and then increase pro- portional to negative time squared. ±rom these Facts, we can obtain the correct answer. 002 (part 1 oF 2) 5 points A particle moves according to the equation x = (10 m / s 2 ) t 2 where x is in meters and t is in seconds. ±ind the average velocity For the time in- terval From t 1 = 2 . 1 s to t 2 = 3 . 95 s. Correct answer: 60 . 5 m / s. Explanation: x = (10 m / s 2 ) t 2 v ave = Δ x Δ t = (10 m / s 2 ) ( t 2 2 - t 2 1 ) t 2 - t 1 = (10 m / s 2 ) [(3 . 95 s) 2 - (2 . 1 s) 2 ] (3 . 95 s) - (2 . 1 s) = 60 . 5 m / s 003 (part 2 oF 2) 5 points ±ind the average velocity For the time interval From t 1 = 2 . 1 s to t 3 = 2 . 2 s. Correct answer: 43 m / s. Explanation: v ave = Δ x Δ t = (10 m / s 2 ) ( t 2 3 - t 2 1 ) t 3 - t 1 = (10 m / s 2 ) [(2 . 2 s) 2 - (2 . 1 s) 2 ] (2 . 2 s) - (2 . 1 s) = 43 m / s 004 (part 1 oF 1) 0 points The acceleration oF an object, starting From rest, is shown on the graph below.
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Answer, Key – Homework 2 – David McIntyre – 45123 – Mar 25, 2004 2 t(s) a(m/s 2 ) 5 -5 1 2 3 4 5 Other than at t = 0, when is the velocity of the object equal to zero? 1.
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This note was uploaded on 09/15/2009 for the course PHY 557 taught by Professor Rijssenbeek during the Spring '08 term at Adelphi.

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hw2_solns - Answer, Key Homework 2 David McIntyre 45123 Mar...

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