Question

A vehicle was stopped in 3 seconds by fully jamming the brakes. The skid marks measured 12 metres. The average skid resistance coefficient will be

• A. 0.15
• B. 0.52
• C. 0.33
• D. 0.27

Answer 1

The correct option is D 0.27

Initial speed of vehicle,
$V=at$
$anda=fg$
$\therefore V=fgt$
$AlsoS=\frac{V^2}{2fg}=\frac{f^2{g}^2{t}^2}{2fg}$

$\Rightarrow f=\frac{2S}{g{t}^2}=\frac{2\times 12}{9.81\times {\left(3\right)}^2}$

$\Rightarrow f=0.27$