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Unformatted text preview: Thevalingam, Donald – Homework 30 – Due: Apr 30 2007, midnight – Inst: Eslami 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points The center of mass of a pitched baseball or radius 5 . 36 cm moves at 18 . 3 m / s. The ball spins about an axis through its center of mass with an angular speed of 50 . 2 rad / s. Calculate the ratio of the rotational energy to the translational kinetic energy. Treat the ball as a uniform sphere. 002 (part 1 of 1) 10 points A circular disk with a mass m and radius R is mounted at its center, about which it can rotate freely. The disk has moment of inertia I = 1 2 m R 2 . A light cord wrapped around it supports a weight m g . R I ω m T g Find the total kinetic energy of the system, when the weight is moving at a speed v . 1. K = 1 2 m v 2 2. K = 3 4 m v 2 3. K = m v 2 4. K = 4 5 m v 2 5. K = 1 3 m v 2 6. K = 5 2 m v 2 7. K = 3 2 m v 2 8. K = 2 3 m v 2 9. K = 5 4 m v 2 003 (part 1 of 3) 10 points For any given rotational axis, the radius of gyration, K , of a rigid body is defined by the expression K 2 = I M , where M is the total mass of the body and I is the moment of inertia about the given axis. In other words, the radius of gyration is the distance between an imaginary point mass M , and the axis of rotation with I for the point mass about that axis is the same as for the rigid body. Find the radius of gyration of a solid disk of radius 3 . 93 m rotating about a central axis. Answer in units of m. 004 (part 2 of 3) 10 points Find the radius of gyration of a uniform rod of length 7 . 73 m rotating about a central axis....
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This note was uploaded on 04/05/2010 for the course PHY 52033 taught by Professor Tleva during the Spring '10 term at University of Texas at Austin.
- Spring '10