Question

How large must the coefficient of static friction be between the tires and the road if a car is to round a level curve of radius 90 m at a speed of 90 km/h ?

Answer 1

The coefficient of static friction will be 0.7

Step-by-step explanation:

Given data

the radius of curve= 90m

speed v= 90 km/h to m/s = (90*100)/60*60= 25 m/s

we know that the expression for the centripetal force acting on the car

`Fc= (mv^2)/(r)`-------1

we also know that the expression for the frictional force between road and tire.

Ff= μmg--------2

Equating equation 1 and 2 we have

μmg= mv^2/r

μ= v^2/gr

substituting the values of speed and radius we have (assuming g= 9.81m/s^2)

μ= 25^2/9.81*90

μ= 625/882.9

μ= 0.7