Question

A vehicle moving at 40 kmph was stopped by applying the brakes and the length of skid mark was 16.6 m. If the average skid resistance of the pavement is known to be 0.70 , then the value of brake efficiency of the test vehicle will be

Answer 1

$\text{Length of skid marks,}L=16.6m$
$\text{Average pavement skid resistance,}f=0.70$
$Speedofvehicle,v=40\times \frac{5}{18}=11.11m/s$
Now, average skid resistance developed is given by,
$f^{\prime }=\frac{V^2}{2gL}$
$=\frac{{11.11}^2}{2\times 9.81\times 16.6}=0.379$
$\therefore Brakeefficiency=\frac{0.379}{0.7}\times 100=54.14\%$