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coker exam

# coker exam - Version 040 Quiz 2 coker(58245 This print-out...

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Version 040 – Quiz 2 – coker – (58245) 1 This print-out should have 24 questions. Multiple-choice 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 m g h i = 1 2 k x 2 x = radicalbigg 2 m g h i k = radicalBigg 2 (0 . 059 kg) (9 . 8 m / s 2 ) (1 . 9 m) 13 N / m = 0 . 411111 m . 002 10.0 points For this problem, we assume that we are on Planet-I. 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 Planet-I 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 Planet-I. 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.

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Version 040 – Quiz 2 – coker – (58245) 2 Explanation: For r > R , the potential energy of the cannon ball is U = G M m r . Since g I = G M R 2 , U = m g 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. 004 (part 1 of 2) 10.0 points Consider a force of 73 . 6 N, pulling 3 blocks of identical masses, where each mass is 0 . 9 kg, along a rough horizontal surface. The coef- ficient of kinetic friction between the blocks and the surface is given by 0 . 6. The accelera- tion of the blocks is a .
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coker exam - Version 040 Quiz 2 coker(58245 This print-out...

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