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Unformatted text preview: Version 040 Quiz 2 coker (58245) 1 This printout should have 24 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. Quiz 2 covers only topics covered in class lectures over Chs. 6, 7, 8 and 9 in Oha nian/Markert. 001 10.0 points A 59 g block is released from rest and slides down a frictionless track that begins 1 . 9 m above the horizontal, as shown in the figure. At the bottom of the track, where the surface is horizontal, the block strikes and sticks to a light spring with a spring constant of 13 N / m. The acceleration of gravity is 9 . 8 m / s 2 . 1 . 9 m 59 g 13 N / m Find the maximum distance the spring is compressed. 1. 0.350392 2. 0.206738 3. 0.249837 4. 0.411111 5. 0.217188 6. 0.284493 7. 0.344828 8. 0.306496 9. 0.196167 10. 0.180263 Correct answer: 0 . 411111 m. Explanation: Let : m = 59 g = 0 . 059 kg , h i = 1 . 9 m , and k = 13 N / m . From conservation of mechanical energy, we have mg h i = 1 2 k x 2 x = radicalbigg 2 mg h i k = radicalBigg 2 (0 . 059 kg) (9 . 8 m / s 2 )(1 . 9 m) 13 N / m = . 411111 m . 002 10.0 points For this problem, we assume that we are on PlanetI. The radius of this planet is R =2390 km, the gravitational acceleration at the surface is g I =8 . 35 m / s 2 , and the grav itational constant G = 6 . 67 10 11 N m 2 /kg 2 in SI units. The mass of PlanetI is not given. Not all the quantities given here will be used. Suppose a cannon ball of mass m = 5090 kg is projected vertically upward from the sur face of this planet. It rises to a maximum height h =7600 . 2 km above the surface of the planet. Caution: Here the gravitational accelera tion decreases as the cannon ball travels away from PlanetI. R h Determine the kinetic energy (in Joules) of the cannon ball immediately after it is fired off. 1. 28675000000.0 2. 93699500000.0 3. 77277500000.0 4. 99814500000.0 5. 24246500000.0 6. 171427000000.0 7. 64253700000.0 8. 55935700000.0 9. 105450000000.0 10. 96064400000.0 Correct answer: 7 . 72775 10 10 J. Version 040 Quiz 2 coker (58245) 2 Explanation: For r > R , the potential energy of the cannon ball is U = GM m r . Since g I = GM R 2 , U = mg I R 2 r . Apply conservation of energy: E = K i + U i = K f + U f K i = U f U i = mg I R 2 /r ( mg I R ) = mg I R (1 R/r ), where r = R + h . 003 10.0 points How does the force of gravity between two bodies change when the distance between them doubles? 1. Unable to determine; the mass is needed. 2. halves 3. quadruples 4. drops to one quarter of its original value correct 5. remains the same 6. doubles Explanation: The force of gravity between two bodies is inversely proportional to the square of the distance separating them parenleftbigg F 1 r 2 parenrightbigg , so the force of gravity will be F 1 (2 r ) 2 = 1 4 1 r 2 1 4 F , i.e. , one fourth of its original value....
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This note was uploaded on 03/04/2010 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Turner
 Physics

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