Question

A policeman investigating an accident measures the skid marks left by a car on the horizontal road. He determines that the distance was 23.74 n. The coefficient of kinetic friction between the tires and the road is μk = 0.29 How fast was the car going when the driver applied the brakes

Answer 1

The velocity of car was m m/s

Explanation:

When the car skids , its centripetal force is provided by frictional force .

Here centripetal force F = $\frac{mv^2}{r}$

here v is the velocity of car and r is the radius of the curve .

The frictional force f = μ R

here μ is the coefficient of kinetic friction and R is normal reaction

Thus f =  m g

On horizontal road R = mg

Thus F = f  at the time of skid .

Thus v = $\sqrt{\mu rg}$

= $\sqrt{0.29x23.74x10}$ = 9 m/s