posted by Sam .
An automobile with 0.310 m radius tires travels 85,000 km before wearing them out. How many revolutions do the tires make, neglecting any backing up and any change in radius due to wear?
Circumference = pi * 2r = 3.14 * 0.620 =
8.5*10^7m * 1rev/1.95m = 4.36*10^7 Revs
= 43.6 Million Revs.