Answer:
43 revolutions.
Explanation:
The time it takes for the car to stop is
[tex]t=v_i/a=\frac{17.7m/s}{1.38m/s^2}=12.83s[/tex]
The distance it travels in that time is
[tex]d=\frac{1}{2}at^2=\frac{1}{2}(1.38)(12.83) ^2=113.5m[/tex]
The number of revolutions that the tires make is then
[tex]n=\frac{d}{2\pi r} =\frac{113.5}{2\pi *0.42} =\boxed{43\:revolutions}[/tex]
The last calculation just asks the question "how many tire circumferences fit into d=113 meters?"
