S equals square root of 30 times D times f times n end root

Question

Where:

S = speed in miles per hour
30 = a constant value used in the equation
D = length of the skid marks in feet
f = drag factor for the road surface
n = braking efficiency as a percent

If a car’s speed is 70 miles per hour on a road surface with a drag factor of 0.50 and with a breaking efficiency of 85% (n = .85), what would be the length of the skid marks? Round to the nearest tenth.

Answer 1

S=sqrt(30*D*f*n)
s^2=30*D*f*n
d=70^2/(30*.5*.85) about 385 feet. check that