90. We use conservation of mechanical energy. The center of mass is at the midpoint of the cross bar of the Hand it drops by L/2, where Lis the length of any one of the rods. The gravitational potential energy decreases by MgL/2, where Mis the mass of the body. The initial kinetic energy is zero and the final kinetic energy may be written 122Iω,whereIis the rotational inertia of the body and is its angular velocity when it is vertical. Thus,022=−+¡=MgLIMgL I//.12ωωSince the rods are thin the one along the axis of rotation does not contribute to the
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This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.