Fundamentals of Transportation/Sight Distance/Solution

TProblem

Problem:

You see a body lying across the road and need to stop. If your vehicle was initially traveling at 100 km/h and skids to a stop on a 2.5% upgrade, taking 75 m to do so, what was the coefficient of friction on this surface?

Example

Solution:

$d_b=\frac{{\left(100\ast \left(\frac{1000}{3600}\right)\right)}^2-{\left(0\right)}^2}{2\ast \left(9.8\right)\ast \left(f+0.025\right)}=75m$

$\left(f+0.025\right)=\frac{{\left(27.78\right)}^2}{2\ast \left(9.8\right)\ast 75}$

$f=0.50$