Question

Police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d=(s^2)/(30.25) where s is the speed in miles per hour and d is the length of the vehicle’s skid marks. What was the approximate speed of a vehicle that left a skid mark measuring 140 feet?

Answer 1

We know that 0.75d=(s^2)/(30.25) , so for d=140ft
0.75 x 140= (s^2)/(30.25)  implies   0.75 x 140 x 30.25)= (s^2), and then
s= sqrt( 0.75 x 140 x 30.25)=56.35 miles /hour