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Unformatted text preview: sindt (as53996) HW 2 Opyrchal (11101) 1 This printout should have 17 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A car travels along a straight stretch of road. It proceeds for 15 . 9 mi at 53 mi / h, then 27 . 3 mi at 41 mi / h, and finally 40 . 6 mi at 38 . 1 mi / h. What is the cars average velocity during the entire trip? Correct answer: 41 . 2509 mi / h. Explanation: Let : d A = 15 . 9 mi , v A = 53 mi / h , d B = 27 . 3 mi , v B = 41 mi / h , d C = 40 . 6 mi , and v C = 38 . 1 mi / h . The total time the car spent on the road is t = d A v A + d B v B + d C v C = 15 . 9 mi 53 mi / h + 27 . 3 mi 41 mi / h + 40 . 6 mi 38 . 1 mi / h = 2 . 03147 h , so the average velocity is v = d t = d A + d B + d C t = 15 . 9 mi + 27 . 3 mi + 40 . 6 mi 2 . 03147 h = 41 . 2509 mi / h . 002 (part 1 of 3) 10.0 points Consider the plot below describing motion along a straight line with an initial position of x = 10 m. 1 1 2 3 1 2 3 4 5 6 7 8 9 b b b b b time (s) velocity(m/s) What is the position at 2 seconds? Correct answer: 13 m. Explanation: The initial position given in the problem is 10 m. b b b b b b b b 1 2 3 4 5 6 7 8 9 1 2 3 1 time (s) velocity(m/s) The position at 2 seconds is 10 meters plus the area of the triangle (shaded in the above plot) x = 10 m + 1 2 (2 s 0 s) (3 m / s 0 m / s) = 13 m ; however, it can also be calculated: x = x i + v i ( t f t i ) + 1 2 ( t f t i ) 2 = (10 m) + (0 m / s) (2 s 0 s) + 1 2 (1 . 5 m / s 2 ) (2 s 0 s) 2 = 13 m . 003 (part 2 of 3) 10.0 points What is the position at 6 seconds? Correct answer: 21 m....
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This note was uploaded on 11/09/2010 for the course PHYSICS 111 taught by Professor Wang during the Spring '09 term at NJIT.
 Spring '09
 WANG
 Physics

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