# 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.

Result

k =  2.18

#### Solution:

$r=200 \ \text{m} \ \\ v=108 \ km/h=108 / 3.6 \ m/s=30 \ m/s \ \\ g=9.81 \ \text{m/s}^2 \ \\ \ \\ F_g=mg \ \\ F_o=m v^2 / r \ \\ \ \\ F_o k=F_g \ \\ m v^2 / r k=m g \ \\ \ \\ k=g \cdot \ r / v^2=9.81 \cdot \ 200 / 30^2=\dfrac{ 109 }{ 50 }=2.18$

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