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Unformatted text preview: schroeder (cs39963) Quiz 4: Two Dimensional Motion  Projectile and Circular Moton balasubraman This printout should have 31 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A projectile is fired straight upward at 166 m / s. How fast is it moving at the instant it reaches the top of its trajectory? Correct answer: 0 m / s. Explanation: At the top of the trajectory the vertical component of the speed of the projectile is zero, so the speed is simply the horizontal component of the initial velocity. v = v x = 0 m / s 002 (part 2 of 2) 10.0 points How fast is it moving at the instant it reaches the top of its trajectory if the projectile is fired upward at 23 from the horizontal? Correct answer: 152 . 804 m / s. Explanation: v = v x = v cos = (166 m / s) cos23 = 152 . 804 m / s . 003 (part 1 of 3) 10.0 points A boy throws a ball upward. Compare the magnitudes of the gravitational accelerations at three points along the path of the ball. Point A is before the ball reaches the top. a) Point A on the way up. b) Point B is at the top. c) Point C is after it has passed the top and on the way down. B A C The magnitudes of the acceleration are re lated as 1. a A < a B . 2. a A = g . correct Explanation: The gravitational acceleration near the sur face of the earth is a constant, so the correct choice is a A = g . 004 (part 2 of 3) 10.0 points The magnitudes of the acceleration are re lated as 1. a B > a C . 2. a B = a A . correct 3. a B = 0 . Explanation: The gravitational acceleration near the sur face of the earth is a constant, so the correct choice is a B = a A . 005 (part 3 of 3) 10.0 points The magnitudes of the acceleration are re lated as 1. a C = a B = a A . correct 2. a C < a B and a A < a B . Explanation: The gravitational acceleration near the sur face of the earth is a constant, so the correct choice is a C = a B = a A . 006 (part 1 of 2) 10.0 points A particle has a constant acceleration vectora = schroeder (cs39963) Quiz 4: Two Dimensional Motion  Projectile and Circular Moton balasubraman (4 m / s 2 ) . At t = 2 sec, it has velocity vectorv = ( + ) (2 m / s). What is its velocity at t = 0? 1. (4 m / s) + (4 m / s) 2. vector 3. (2 m / s) + (6 m / s) 4. (2 m / s) (6 m / s) correct 5. (4 m / s) (4 m / s) Explanation: vectorv ( t ) = vectorv (0) + vectorat , so vectorv (0) = vectorv ( t ) vectorat = ( + ) (2 m / s) (4 m / s 2 )(2 s) = (2 m / s) + (2 m / s 8 m / s) = (2 m / s) (6 m / s) . 007 (part 2 of 2) 10.0 points After 2 sec, its position is found to be vectorr = ( ) (4 m)....
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 Fall '08
 STAFF
 Physics

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