Answer:
610.02 rpm
Step-by-step explanation:
You want to know the rotational speed of a 27-inch tire on a car moving 49 miles per hour.
Inches
A mile is 5280 feet, and each foot is 12 inches. Then 49 miles will be ...
(49 mi)(5280 ft/mi)(12 in/ft) = 3104640 in
An hour is 60 minutes, so 1/60 of this distance will be traveled in 1 minute
3104640 in/(60 min) = 51744 in/min
Revolution
The distance around the tire is given by ...
C = πd
C = π(27 in) = 27π in . . . . . . . distance for one revolution
RPM
The rotation rate in revolutions per minute is the number of times the tire travels a distance equal to its circumference in one minute.
(51744 in/min)/(27π in/rev) ≈ 610.02 rev/min
The tires are turning about 610.02 revolutions per minute.
