Angular Speed problem?

birdman

A car is moving at the rate of 50 miles per hour, and the diameter of its wheels is 2.5 feet.

(a) Find the number of revolutions per minute that the wheels are rotating

(b) Find the angular speed of the wheels in radians per minute

em

(a)

(50 miles/hr)(5280 ft/mile)(rev / 2π(2.5 ft))(hr / 60 min) = 280 rev/min

(b)

(280 rev/min)(2π rad/rev) = 1760 rad/min