Chapter 8, Problem 2C

A cyclometer is a device mounted on a bicycle that records and displays trip information such as elapsed time, distance traveled, and average speed. Modern versions employ small magnets attached to a spoke on either the front or rear wheel and a sensor located on the front fork or rear frame. As the magnet is carried past the detector once each wheel revolution, it produces an electrical pulse that is recorded and logged by an integrated circuit in the device. The distance traveled equals the total number of revolutions multiplied by the circumference of the wheel.
(a) A typical mountain bike has a wheel diameter of 26 in. How far will a cyclist have traveled in both miles and kilometers if her cyclometer indicates that her front wheel has made 25,000 revolutions during her trip?
(b) If the cyclometer clock shows that the elapsed time for the trip was 2 hours and 40 minutes, what was the rider’s average speed during this period?