quiz4v1sol - Ph 111 November 5, 2008 NAME _RWB_ Quiz 4...

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Ph 111 NAME ________RWB _______________________ November 5, 2008 Quiz 4 Solutions Please give your numerical answers to at least three significant figures. Please give the correct units (m/s, kg, rad/s, hour, day, etc.) with each answer. Problem 1. Two turtles, each of mass M = 2.4 kg, sit on an approximately massless branch in the water. They sit on opposite sides of the center, each a distance R = 1.4 m from the center of the branch. (a) What is the moment of inertia of the system of branch and two turtles, about the center of the branch? Just MR 2 for each turtle: () ( ) 2 22 2 2 2.4 kg 1.4 m 9.408 kg-m IM R == = (b) Suppose that the branch is initially rotating at a rate of ω = 0.34 radians/sec. Then two more identical turtles, with the same mass as the others, jump onto the branch, right next to the turtles already there. The new turtles are not moving when they jump onto the branch. What is the new angular rate of rotation? Conservation of angular momentum says before before after after LI I The moment of inertia doubles; so the angular velocity is reduced by a factor of 1/2.
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