## College Physics (4th Edition)

(a) The ball has turned through 18.5 revolutions. (b )The ball's angular speed is $18.1~rad/s$
(a) We can find the angle $\theta$ through which the ball has rotated: $\theta = \frac{d}{r} = \frac{18~m}{0.155~m} = 116~rad$ We can convert from units of radians to revolutions: $116~rad \times \frac{1~rev}{2\pi~rad} = 18.5~rev$ The ball has turned through 18.5 revolutions. (b) We can find the ball's angular speed: $\omega = \frac{v}{r} = \frac{2.8~m/s}{0.155~m} = 18.1~rad/s$ The ball's angular speed is $18.1~rad/s$.