Skid friction

Find the smallest coefficient of skid friction between the car tires and the road so that the car can drive at a 200 m radius at 108 km/h and does not skid.

Correct answer:

k =  2.18

Step-by-step explanation:

$$\begin{gathered} r=200\text{m} \\ v=108\text{km/h}\to \text{m/s}=108:3.6\text{m/s}=30\text{m/s} \\ g=9.81{\text{m/s}}^2 \\ {F}_g=mg \\ {F}_o=m{v}^2/r \\ {F}_{o}k=F_g \\ m{v}^2/rk=mg \\ k=g\cdot r/v^2=9.81\cdot 200/30^2=2.18 \end{gathered}$$

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