# Homework Help: Revolutions of a tire and angle in radians thru warranty

1. Feb 29, 2012

### chaotiiic

1. The problem statement, all variables and given/known data
The tires on a new car have a radius of .275 meters and are warranted for 75,000km

a)what is the angle in radians that one of these tires will rotate thru in the warranty period?
b) how many revolutions does this make?

2. Relevant equations
circumference = 2pi*r

3. The attempt at a solution
circumference = (2pi)(.275m) = 1.727m
b) 75m/.001727= 43427.9
a) 43427 *2pi = 272865

2. Feb 29, 2012

### Pengwuino

Your calculation for b) is wrong. You should find the number of revolutions as ${{75,000,000m}\over{1.727 {{m}\over{turn}}}}$

3. Feb 29, 2012

### chaotiiic

43,427,909.66 revolutions.
to find the angle do i multiply this by 2pi?

4. Feb 29, 2012

Yes.