
Mike D. answered 09/04/21
Experienced high school discrete math teacher
I mile = 5280 feet = 5280 x 12 = 63360 inches.
1 hour = 60 minutes.
So inches per minute that a point on the circumference moves = ( 63360 x 20) / 60 = 21120
The radius of the wheel is 26 /2 = 13 inches
So circumference = 2πr = 26π
So the wheel will turn through 21120 / 26π circumferences in a minute
1 circumference is 2π radians, so 21120 / 26π x 2π = (21120 x 2) / 26 radians per minute