Question

 If the coefficient of friction between tires and roadway is 0.50, what is the smallest radius at which 

     a car can turn on a horizontal road when its speed is 30 miles/hour? 

Answer 1

Given:

$\mu=0.5$

$v=30\:\rm mi/hr=13.4\: m/s$

$$ma=F$$

$$\frac{mv^2}{R}=\mu N=\mu m g$$

$$R=v^2/(\mu g)\\ =(13.4)^2/(0.5*9.8)=37\:\rm m$$