# Ch10 HW2 - WebAssign Ch10 HW2 (Homework) Current Score: 42...

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Ch10 HW2 (Homework) Arthur Barfield PHYS 2211, section M, Fall 2008 Instructor: Jennifer Curtis Web Assign Current Score: 42 out of 42 Due: Friday, November 7, 2008 09:00 AM EST Description Rotational and translational angular momentum; Rotational kinetic energy Instructions Section 10.2 In this assignment you are allowed 3 submissions per numeric question part, and 2 submissions per multiple choice question part The due date for this assignment is past. Your work can be viewed below, but no changes can be made. 1. [MI2 10.X.09.01] 3/3 points Mounted on a low-mass rod of length 0.48 m are four balls. Two balls (shown in red on the diagram), each of mass 0.75 kg, are mounted at opposite ends of the rod. Two other balls, each of mass 0.23 kg (shown in blue on the diagram), are each mounted a distance 0.12 m from the center of the rod. The rod rotates on an axle through the center of the rod (indicated by the "x" in the diagram), perpendicular to the rod, and it takes 1.5 seconds to make one full rotation. (a) What is the moment of inertia of the device about its center? = .0930 0.093 kg · m 2 (b) What is the angular speed of the rotating device? = 4.19 4.19 radians/s (c) What is the magnitude of the angular momentum of the rotating device? = .3898 0.39 kg · m 2 /s

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Solution or Explanation (a) Each mass contributes an amount mr 2 to the moment of inertia, so I = 2m 1 r 1 2 + 2m 2 r 2 2 (b) = 2 / T . (c) The angular momentum is . 2. [MI2 10.X.09] 8/8 points Moments of intertia for some objects of uniform density: disk I = (1/2) MR 2 , cylinder I = (1/2) MR 2 , sphere I = (2/5) MR 2 (a) A uniform disk has a moment of inertia that is (1/2) MR 2 . A uniform disk of mass 14 kg, thickness 0.3 m, and radius 0.5 m is located at the origin, oriented with its axis along the y axis. It rotates clockwise around its axis when viewed from above (that is, you stand at a point on the +y axis and look toward the origin at the disk). The disk makes one complete rotation every 0.1 s. What is the rotational angular momentum of the disk?
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## This note was uploaded on 04/19/2010 for the course PHYS 2212 taught by Professor Kindermann during the Spring '09 term at Georgia Institute of Technology.

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Ch10 HW2 - WebAssign Ch10 HW2 (Homework) Current Score: 42...

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