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Unformatted text preview: patel (ap27536) – Circular Motion – cao – (10519) 1 This printout should have 11 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points An amusement park ride consists of a rotating circular platform 8 . 62 m in diameter from which 10 kg seats are suspended at the end of 3 . 2 m massless chains. When the system rotates, the chains make an angle of 39 . 7 ◦ with the vertical. The acceleration of gravity is 9 . 8 m / s 2 . θ l d What is the speed of each seat? Correct answer: 7 . 19009 m / s. Explanation: In the vertical direction we have T cos θ = mg , where T is the tension in the chain. In the horizontal direction we have T sin θ = mv 2 r . Since r = ℓ sin θ + d 2 = (3 . 2 m) sin39 . 7 ◦ + 8 . 62 m 2 = 6 . 35406 m , we have v = radicalbig g r tan θ = radicalBig (9 . 8 m / s 2 ) (6 . 35406 m) tan39 . 7 ◦ = 7 . 19009 m / s . 002 (part 2 of 2) 10.0 points If a child of mass 45 . 9 kg sits in a seat, what is the tension in the chain (for the same angle)? Correct answer: 712 . 01 N. Explanation: M = 45 . 9 kg From the first part we have T cos θ = ( m + M ) g T = ( m + M ) g cos θ = (10 kg + 45 . 9 kg) (9 . 8 m / s 2 ) cos 39 . 7 ◦ = 712 . 01 N . 003 (part 1 of 2) 10.0 points An amusement park ride consists of a large vertical cylinder that spins about its axis fast enough that any person inside is held up against the wall when the floor drops away (see figure). The coefficient of static friction between the person and the wall is μ and the radius of the cylinder is R . ω R What is the minimum tangential velocity needed to keep the person from slipping down ward? 1. v = radicalbig 2 μg R 2. v = μ radicalbig 2 π g R 3. v = 2 μ radicalbig g R 4. v = μ radicalbig g R patel (ap27536) – Circular Motion – cao – (10519) 2 5. v = radicalBigg g R μ correct 6. v = radicalbig g R 7. v = 1 2 radicalbig g R 8. v = 2 radicalbig g R 9. v = 1 μ radicalbig g R 10. v = μ radicalbig 2 g R Explanation: Basic Concepts:...
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This note was uploaded on 10/20/2009 for the course PHYS 105 taught by Professor Ken during the Fall '08 term at NJIT.
 Fall '08
 KEN
 Circular Motion, Work

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