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Unformatted text preview: lavallo (jhl936) Homework 14 florin (58140) 1 This printout should have 21 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A solid sphere of radius 23 cm is positioned at the top of an incline that makes 27 angle with the horizontal. This initial position of the sphere is a vertical distance 3 . 1 m above its position when at the bottom of the incline. The sphere is released and moves down the incline. 23 cm M 27 3 . 1m Calculate the speed of the sphere when it reaches the bottom of the incline if it rolls without slipping. The acceleration of gravity is 9 . 8 m / s 2 . The moment of inertia of a sphere with respect to an axis through its center is 2 5 M R 2 . Answer in units of m / s. 002 10.0 points The top in the figure has moment of inertia . 000638 kg m 2 and is initially at rest. It is free to rotate about the stationary axis AA . A string wrapped around a peg along the axis of the top is pulled in such a manner as to maintain a constant tension of 3 . 61 N. F A A' If the string does not slip while being un wound, what is the angular speed of the top after 121 cm of string has been pulled off of the peg? Answer in units of rad / s. 003 10.0 points A system of two wheels fixed to each other is free to rotate about a frictionless axis through the common center of the wheels and per pendicular to the page. Four forces are ex erted tangentially to the rims of the wheels, as shown below. F 2 F F F 2 R 3 R What is the magnitude of the net torque on the system about the axis? 1. = 2 F R 2. = 0 3. = 5 F R 4. = 14 F R 5. = F R 004 10.0 points A rod can pivot at one end and is free to rotate without friction about a vertical axis, as shown. A force vector F is applied at the other end, at an angle to the rod. L m F If vector F were to be applied perpendicular to the rod, at what distance d from the axis lavallo (jhl936) Homework 14 florin (58140) 2 of rotation should it be applied in order to produce the same torque vector ? 1. d = L sin 2. d = L 3. d = L cos 4. d = L tan 5. d = 2 L 005 10.0 points A spool (similar to a yoyo) is pulled in three ways, as shown below. There is sufficient friction for rotation....
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This note was uploaded on 04/09/2010 for the course PHY 58150 taught by Professor Florin during the Spring '10 term at University of Texas at Austin.
 Spring '10
 Florin

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