## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

$\alpha = 47~rad/s^2$
We can convert 1800 rpm to units of rad/s: $\omega = (1800~rpm)(\frac{1~min}{60~s})(\frac{2\pi~rad}{1~rev})$ $\omega = 60\pi~rad/s$ We then find the angular acceleration as: $\alpha = \frac{\Delta \omega}{t}$ $\alpha = \frac{60\pi~rad/s}{4.0~s}$ $\alpha = 47~rad/s^2$