# Chapter 12 - Rotation of a Rigid Body - Exercises and Problems - Page 350: 46

The angular momentum is $-0.025~kg~m^2/s$.

#### Work Step by Step

We can express the angular velocity in units of rad/s. Note that the angular velocity is negative since the rotation is in the clockwise direction. $\omega = -(600~rpm)(\frac{2\pi~rad}{1~rev})(\frac{1~min}{60~s})$ $\omega = -20\pi~rad/s$ We can find the moment of inertia of the disk. $I = \frac{1}{2}MR^2$ $I = \frac{1}{2}(2.0~kg)(0.020~m)^2$ $I = 4.0\times 10^{-4}~kg~m^2$ We can find the angular momentum about the axle. $L = I~\omega$ $L = (4.0\times 10^{-4}~kg~m^2)(-20\pi~rad/s)$ $L = -0.025~kg~m^2/s$ The angular momentum is $-0.025~kg~m^2/s$.

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