Question

Driving 30.7 m/s in your car you see a dog up ahead and slam on your brakes. You stop just before hitting the dog after skidding for 132.1 m. What is the coefficient of friction between the road and your tires?

Answer 1

Answer: 2.74

Explanation:

We can solve this problem using the stopping distance formula:

$d=\frac{(V_{o})^{2}}{2 \mu g}$

Where:

$d=132.1 m$ is the distance traveled by the car before it stops

$V_{o}=30.7 m/s$ is the car's initial velocity

$\mu$ is the coefficient of friction between the road and the tires

$g=9.8 m/s^{2}$ is the acceleration due gravity

Isolating $\mu$:

$\mu=\frac{2dg}{(V_{o})^{2}}$

Solving:

$\mu=\frac{2(132.1 m)(9.8 m/s^{2})}{(30.7 m/s)^{2}}$

$\mu=2.74$ This is the coefficient of friction