The radius of the yaw mark to the nearest tenth of a foot is 11.2 ft
The minimum speed 11.1634 miles per hour.
Yaw marks are always curved. They are, initiated by a steering input. They're what's left from a tire that is still rolling but is simultaneously sliding laterally.
The formula for determining radius from a chord and middle ordinate is
[tex]r^{2}= \frac{c^{2}}{8m}+\frac{m}{2}[/tex]
To find the radius of the yaw mark, we have to use the formula
[tex]r^{2}= \frac{c^{2}}{8m}+\frac{m}{2}[/tex]
where c is the length of the chord and m is the middle ordinate
As the tires leave a yaw mark with a 31 foot chord and a middle ordinate of 3 feet.
So,
[tex]r^{2}= \frac{31^{2}}{8*3}+\frac{3}{2}[/tex]
[tex]r^{2}= 40.041 +1.5\\r^{2}=41.541[/tex]
Now to find the minimum speed, we are going to use the formula: [tex]s=\sqrt{15fr}[/tex]
where 'f' is drag factor and 'r' is the radius
drag factor is 0.2, f=0.2
and r= 41.541 ft
So, [tex]s=\sqrt{15* 0.2*41.541}\\s=\sqrt{124.623}\\s= 11.1634 mph[/tex]
The minimum speed before the brakes are applied was 11.1634 miles per hour.
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