Question

Semi-trailer trucks have an odometer on one hub of a trailer wheel. The hub is weighted so that it does not rotate, but it contains gears to count the number of wheel revolutions—it then calculates the distance traveled. If the wheel has a 1.15 m diameter and goes through 200,000 rotations, how many kilometers should the odometer read?

Answer 1

1445Km

Explanation:

By having the radius we can easily have the circumference of the wheel with the equation that relates both quantities:
`C=2\pi r`

If the wheel turns one time, the distance travelled by the truck will be C (the whole circumference), so to know the total distance travelled we need to know how many times the wheel turns, and multiply this number to the circumference of the wheel, that is:

`d=NC=N2\pi r=2\pi (200000)(1.15m)=1445132.6m=1445Km`