Answer:
1056 radians/min
Explanation:
We can convert the linear speed to inches per minute to help with finding the angular speed.
(12 mi/h) = (12 mi)(5280 ft/mi)(12 in/ft)/((1 h)(60 min/h))
= (12×5280×12/60) in/min = 12,672 in/min
Each radius-length represents 1 radian of arc of the wheel. The radius is half the diameter, 24 in/2 = 12 in, so the angular speed is ...
(12,672 in/min)/(12 in/radian) = 1056 radians/min