This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: kaplan (hmk378) Homework 8 Weathers (17104) 1 This printout should have 12 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 11 m in diameter from which 10 kg seats are suspended at the end of 2 . 61 m massless chains. When the system rotates, the chains make an angle of 14 . 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: 3 . 98035 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 . 61 m) sin 14 . 7 + 11 m 2 = 6 . 16231 m , we have v = radicalbig g r tan = radicalBig (9 . 8 m / s 2 ) (6 . 16231 m) tan14 . 7 = 3 . 98035 m / s . 002 (part 2 of 2) 10.0 points If a child of mass 39 . 6 kg sits in a seat, what is the tension in the chain (for the same angle)? Correct answer: 502 . 529 N. Explanation: M = 39 . 6 kg From the first part we have T cos = ( m + M ) g T = ( m + M ) g cos = (10 kg + 39 . 6 kg) (9 . 8 m / s 2 ) cos 14 . 7 = 502 . 529 N . 003 10.0 points A curve of radius 59 . 9 m is banked so that a car traveling with uniform speed 65 km / hr can round the curve without relying on fric tion to keep it from slipping to its left or right. The acceleration of gravity is 9 . 8 m / s 2 . 1 . 7 M g What is ? Correct answer: 29 . 0457 . Explanation: Let : m = 1700 kg , v = 65 km / hr , r = 59 . 9 m , and . kaplan (hmk378) Homework 8 Weathers (17104) 2 Basic Concepts: Consider the free body diagram for the car. The forces acting on the car are the normal force, the force due to gravity, and possibly friction. N N N cos mg N sin x y To keep an object moving in a circle re quires a force directed toward the center of the circle; the magnitude of the force is F c = ma c = m v 2 r ....
View
Full
Document
 Fall '08
 Weathers
 mechanics, Work

Click to edit the document details