# Quiz 1 - Version 088 – Quiz 1 – Coker –(56625 1 This...

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Unformatted text preview: Version 088 – Quiz 1 – Coker – (56625) 1 This print-out should have 21 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. This is the first and easiest quiz, covering only the material in 3 chapters, Chs. 2, 3 and 4. 001 10.0 points A target lies flat on the ground 9 m from the side of a building that is 10 m tall, as shown below. The acceleration of gravity is 10 m / s 2 . Air resistance is negligible. A student rolls a 9 kg ball off the horizontal roof of the building in the direction of the target. 9 m 10m v 10m The horizontal speed v with which the ball must leave the roof if it is to strike the target is most nearly 1. v = √ 3 9 m/s. 2. v = √ 5 9 m/s. 3. v = 9 √ 5 m/s. 4. v = 9 m/s. 5. v = 6 m/s. 6. v = 9 √ 3 m/s. 7. v = √ 2 9 m/s. 8. v = 9 √ 2 m/s. 9. v = 3 √ 3 m/s. 10. v = 9 √ 2 2 m/s. correct Explanation: m = 9 kg , not required h = 10 m , x = 9 m , and g = 10 m / s 2 . Observe the motion in the vertical direction only and it is a purely 1-dimension movement with a constant acceleration. So the time need for the ball to hit the ground is t = radicalBigg 2 h g and the horizontal speed should be v = x t for the ball to hit the target. Therefore v = x radicalbigg g 2 h = (9 m) radicalBigg 10 m / s 2 2 (10 m) = 9 √ 2 m / s = 9 √ 2 2 m / s . 002 10.0 points Before throwing a 0 . 971 kg discus, an ath- lete rotates it along a circular path of radius 1 . 42 m. The maximum speed of the discus is 17 . 9 m / s. Determine the magnitude of its maximum radial acceleration. 1. 99.8442 2. 225.641 3. 270.054 4. 447.293 5. 280.333 6. 71.9207 Version 088 – Quiz 1 – Coker – (56625) 2 7. 464.0 8. 289.906 9. 209.876 10. 303.343 Correct answer: 225 . 641 m / s 2 . Explanation: The maximum radial acceleration is a r = v 2 r = (17 . 9 m / s) 2 1 . 42 m = 225 . 641 m / s 2 . 003 10.0 points The plot shows x ( t ) for a train moving along a long, straight track. x t Which statement is correct about the mo- tion? 1. The train at first slows down, then speeds up. 2. The train at first speeds up, then slows down. 3. The train moves at constant velocity. 4. The train continually speeds up. 5. The train in fact moves at constant speed along a circular path described by the x ( t ) curve. 6. The train continually slows down and comes to rest. correct Explanation: The slope of x ( t ) continually decreases to reach zero. Since v x ( t ) = d x dt is by definition the slope of x ( t ) at each t , the train continu- ally slows down until it stops. 004 10.0 points Consider the vectors vector A and vector B . vector A vector B Which sketch shows the vector vector A − vector B to the same scale?...
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Quiz 1 - Version 088 – Quiz 1 – Coker –(56625 1 This...

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