Question

How fast is the tire traveling in mph if it does 2 rotations in 2 seconds with a diameter of 27 inches for the tire?

Answer 1

if it does 2 rotations in 2 seconds, then it does
1 rotation in 1 second
or 2π(13.5) inches per second

= 2π(13.5)/12 ft /sec
=7.06858.... ft/s (I stored in in my calculator memory for accuracy)
= (7.06858...)/5280 miles / (1/3600) hr
= appr 4.82 mph

Answer 2

circumference of a circle:

C=2*pi*r
where r=radius=27/2=13.5ft
pi=3.14
C=84.78

It's making 2 rotations every 2 seconds or in other words, 1 rotation every 1 second.


note its asking for mph:
1hour=3600
12inch=1foot
1mile=5280

Formula to solve this:

(n*C*3600)/(12*5280)

where n= number of rotations per sec
C=circumferene, and everything else is conversions to get to mph

(1*84.78*3600)/(12*5280) = 4.816mph

Someone check the work and method just to be sure.