So we have the formula to calculate the speed of a vehicle before the breaks were applied using the measure of it's skid marks: [tex]0.75d= \frac{s^{2} }{30.25} [/tex]
We also know from our problem that the vehicle left a skid mark measuring 160 feet, so [tex]d=160[/tex]. Lets replace that value in our formula to find the speed [tex]s[/tex]:
[tex](0.75)(160)= \frac{s^{2} }{30.25} [/tex]
[tex]120= \frac{s^{2} }{30.25} [/tex]
[tex](120)(30.25)=s ^{2} [/tex]
[tex]s ^{2} =3630[/tex]
[tex]s= \sqrt{3630} [/tex]
[tex]s=60.25[/tex]
We can conclude that the speed of the car before the brakes were applied was about 60 miles per hour.
