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Unformatted text preview: armington (kma786) hw0208 fiete (57165) 1 This printout should have 12 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 particle travels horizontally between two parallel walls separated by 18 . 4 m. It moves toward the opposing wall at a constant rate of 5 . 5 m / s. Also, it has an acceleration in the direction parallel to the walls of 1 . 5 m / s 2 . 18 . 4 m 1 . 5m / s 2 5 . 5 m / s What will be its speed when it hits the opposing wall? Correct answer: 7 . 44528 m / s. Explanation: Let : d = 18 . 4 m , v x = 5 . 5 m / s , a = 1 . 5 m / s 2 , Basic Concepts Kinematics equations v = v o + g t s = s o + v o t + 1 2 g t 2 d a 5 . 01818m / s 5 . 5 m / s 7 . 4 4 5 2 8 m / s 4 7 . 6 2 2 8 8 . 39405 m The horizontal motion will carry the parti cle to the opposite wall, so d = v x t f and t f = d v x = (18 . 4 m) (5 . 5 m / s) = 3 . 34545 s . is the time for the particle to reach the oppo site wall. Horizontally, the particle reaches the maxi mum parallel distance when it hits the oppo site wall at the time of t = d v x , so the final parallel velocity v y is v y = a t = a d v x = (1 . 5 m / s 2 ) (18 . 4 m) (5 . 5 m / s) = 5 . 01818 m / s . The velocities act at right angles to each other, so the resultant velocity is v f = radicalBig v 2 x + v 2 y = radicalBig (5 . 5 m / s) 2 + (5 . 01818 m / s) 2 = 7 . 44528 m / s . 002 (part 2 of 2) 10.0 points armington (kma786) hw0208 fiete (57165) 2 At what angle with the wall will the particle strike? Correct answer: 47 . 6228 . Explanation: When the particle strikes the wall, the ver tical component is the side adjacent and the horizontal component is the side opposite the angle, so tan = v x v y , so = arctan parenleftbigg v x v y parenrightbigg = arctan parenleftbigg 5 . 5 m / s 5 . 01818 m / s parenrightbigg = 47 . 6228 . Note: The distance traveled parallel to the walls is y = 1 2 a t 2 = 1 2 (1 . 5 m / s 2 ) (3 . 34545 s) 2 = 8 . 39405 m . 003 10.0 points Initially (at time t = 0) a particle is mov ing vertically at 7 . 9 m / s and horizontally at 0 m / s. Its horizontal acceleration is 1 . 8 m / s 2 . At what time will the particle be traveling at 39 with respect to the horizontal? The acceleration due to gravity is 9 . 8 m / s 2 ....
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This note was uploaded on 02/11/2011 for the course PHY 301 taught by Professor Swinney during the Spring '07 term at University of Texas at Austin.
 Spring '07
 Swinney
 mechanics

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