## Essential University Physics: Volume 1 (3rd Edition)

$M = 45.2 \ kg$
a) We know that angular momentum is conserved. Thus, we find the initial angular momentum. (Recall, we must convert rpm to radians per second.) $L_i = I\omega=(.22)(13.61)=3$ Using the equation for the moment of inertia of a solid cylinder, we find: $6 = (.31+\frac{1}{2}M(.15)^2)(7.33)$ $M = 45.2 \ kg$ *Note, we set this equal to 6 since the angular momentum changes from 3 to -3, which is a change of 6.