How fast rpm your 20 inch diameter wheel is rotating when yo
     How fast (rpm) your 20 inch diameter wheel is rotating when you driving at 55 mph? 1 mile = 5280 ft., 1 ft. =12 inches.  (Calculator may be used) 
  
  Solution
linear velocity of vehicle/wheel = radius of wheel * angular velocity of wheel
55 mph = (20/2)* Angular velocity
Angular velocity = (55*5280*12)/ (10*60) rpm = 5808 rpm

