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Unformatted text preview: lavallo (jhl936) Homework 06 florin (58140) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A dragster maintains a speedometer reading of 100 km/h and passes through a curve with a constant radius. Which statement is true? 1. All are wrong. 2. The dragster rounded the curve at a changing speed of 100 km/h. 3. The dragster rounded the curve at a changing velocity of 100 km/h. correct 4. The dragster rounded the curve at a con- stant velocity of 100 km/h. 5. The dragster moved along a straight line at a constant velocity of 100 km/h. Explanation: Constant velocity means not only constant speed, but constant direction, so the velocity is changing. A car rounding a curve changes its direction of motion, regardless of its speed. 002 10.0 points A mass slides with negligible friction on a circular track of 1 m radius oriented vertically. Its speed at the position shown in the figure is 3.13 m/s. The acceleration of gravity is 9.8 m/s 2 . v At the position shown in the figure, which of the labeled arrows best represents the di- rection of the acceleration of the mass? 1. 2. 3. The mass is traveling at a constant veloc- ity, therefore it has no acceleration. 4. 5. 6. 7. correct 8. 9. Explanation: The magnitude of the centripetal is a r = v 2 r = (3 . 13 m / s) 2 1 m 9 . 8 m / s 2 . The centripetal acceleration is inward r and gravity is down k . lavallo (jhl936) Homework 06 florin (58140) 2 a a r g 003 10.0 points Calculate the average speed of the Moon around the Earth. The Moon has a period of revolution of 27.3 days and an average dis- tance from the Earth of 3 . 84 10 8 m. 1. 3 . 68245 10 6 m / s 2. 2054.6 m/s 3. 2045.8 m/s 4. 61374 . 2 m / s 5. 1022 . 9 m / s correct 6. 8 . 83789 10 7 m / s 7. None of these 8. 3688.5 m/s 9. 584000 m/s Explanation: Let : T = 27 . 3 d and R = 3 . 84 10 8 m ....
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This note was uploaded on 04/09/2010 for the course PHY 58150 taught by Professor Florin during the Spring '10 term at University of Texas at Austin.
- Spring '10