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Unformatted text preview: fryer (vdf96) Assignment 5.5 Uniform Circular Motion graves (6) 1 This print-out should have 16 questions. Multiple-choice 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 11 m in diameter from which 10 kg seats are suspended at the end of 2 . 87 m massless chains. When the system rotates, the chains make an angle of 33 . 7 with the vertical. The acceleration of gravity is 9 . 8 m / s 2 . l d What is the speed of each seat? Correct answer: 6 . 80841 m / s. Explanation: In the vertical direction we have T cos = mg , where T is the tension in the chain. In the horizontal direction we have T sin = mv 2 r . Since r = sin + d 2 = (2 . 87 m) sin 33 . 7 + 11 m 2 = 7 . 0924 m , we have v = radicalbig g r tan = radicalBig (9 . 8 m / s 2 ) (7 . 0924 m) tan33 . 7 = 6 . 80841 m / s . 002 (part 2 of 2) 10.0 points If a child of mass 33 . 6 kg sits in a seat, what is the tension in the chain (for the same angle)? Correct answer: 513 . 586 N. Explanation: M = 33 . 6 kg From the first part we have T cos = ( m + M ) g T = ( m + M ) g cos = (10 kg + 33 . 6 kg) (9 . 8 m / s 2 ) cos 33 . 7 = 513 . 586 N . 003 10.0 points As viewed by a bystander, a rider in a barrel of fun at a carnival finds herself stuck with her back to the wall. Which diagram correctly shows the forces acting on her? 1. 2. None of the other choices 3. fryer (vdf96) Assignment 5.5 Uniform Circular Motion graves (6) 2 4. 5. 6. correct Explanation: The normal force of the wall on the rider provides the centripetal acceleration neces- sary to keep her going around in a circle. The downward force of gravity is equal and oppo- site to the upward frictional force on her. Note: Since this problem states that it is viewed by a bystander, we assume that the free-body diagrams are in an inertial frame. 004 10.0 points A ball rolls around a circular wall, as shown in the figure below. The wall ends at point X . A B C D E X When the ball gets to X , which path does the ball follow? 1. Path B 2. Path C correct 3. Path D 4. Path A 5. Path E Explanation: As soon as the ball reaches point X the centripetal force is removed, so the ball moves in a straight line (tangent to the circle at oint X)....
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