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

(a) $\omega = 0$ (b) $\alpha$ is negative
(a) Since the pendulum is at one end of its arc, the pendulum is momentarily at rest. Therefore $\omega = 0$ (b) Although the pendulum is momentarily at rest, the angular acceleration $\alpha$ is non-zero and it is directed in the clockwise direction. Since the clockwise direction is considered the negative direction, $\alpha$ is negative.