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08 - fryer(vdf96 Assignment 5.5 Uniform Circular Motion...

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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(part1of2)10.0points 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 . θ l d What is the speed of each seat? Correct answer: 6 . 80841 m / s. Explanation: In the vertical direction we have T cos θ = m g , where T is the tension in the chain. In the horizontal direction we have T sin θ = m v 2 r . Since r = sin θ + d 2 = (2 . 87 m) sin 33 . 7 + 11 m 2 = 7 . 0924 m , we have v = radicalbig g r tan θ = radicalBig (9 . 8 m / s 2 ) (7 . 0924 m) tan 33 . 7 = 6 . 80841 m / s . 002(part2of2)10.0points 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 θ = ( m + M ) g T = ( m + M ) g cos θ = (10 kg + 33 . 6 kg) (9 . 8 m / s 2 ) cos 33 . 7 = 513 . 586 N . 003 10.0points As viewed by a bystander, a rider in a “barrel of fun” at a carnival finds herself stuck with her back to the wall. ω Which diagram correctly shows the forces acting on her? 1. 2. None of the other choices 3.

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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 10.0points 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). Path C is the correct answer. 005 10.0points When you are in the front passenger seat of a car turning to the left, you may find yourself pressed against the right-side door.
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