Question

A vehicle travelling on dry, level pavement at 80 kmph had the brakes applied. The vehicle travelled 76.5 m before stopping. What is the coefficient of friction that has developed ?

• A. 0.4
• B. 0.2
• C. 0.3
• D. 0.33

Answer 1

The correct option is D 0.33

After the application of brakes, the work done against the frictional force for stopping the vehicle will be equal to the kinetic energy of the vehicle.

$\frac{1}{2}m{v}^2=\mu mg.l$
$\frac{1}{2}{(80\times \frac{5}{18})}^2=\mu \times 9.81\times 76.5$
$\mu =0.33$