Question

A car travels at 25 m/s along a horizontal curve of a radius of 450m. What is the minimum coefficient of friction between the tires and the road in order to not skid?

Answer 1

As the car travels along the horizontal curve, the friction force provides necessary centripetal force:

$$F_c=F_{fr},$$ $$\dfrac{mv^2}{r}=\mu mg,$$ $$\mu=\dfrac{v^2}{rg},$$ $$\mu=\dfrac{(25\ \dfrac{m}{s})^2}{450\ m\cdot9.8\ \dfrac{m}{s^2}}=0.14$$