Braking Distance Braking Distance The distance a car

Braking Distance

Braking Distance �The distance a car travels while it is trying to stop is called the braking or stopping distance.

Types of Tires

Braking Distance �The slope or grade of the road and the frictional resistance between the road and the car’s tires can affect the braking distance.

�Eg. Car with new tires on a dry, level road will have a shorter braking distance than one with worn tires on a wet road.

Explaining Breaking Distance �Braking distance is proportional to the square of the velocity of the vehicle. �Eg. If you double your speed, the braking distance increases four times (2 ). If you triple your speed, your braking distance increases nine times (3 ).

Formula for Breaking Distance �Braking distance is also dependent upon the friction between the two surfaces. We account for the frictional effects by using a mathematical constant for different kinds of surfaces. �d �d = kv 2 = braking distance �k = frictional constant (different for each surface) �v = velocity (m/s)

Types of Surfaces

Try an example… �Eg. Find the braking distance for a car with a velocity of 50 km/h on dry pavement.

Reaction Time �Calculations for braking distance are for ideal cases only. In reality the driver’s reaction time also plays a role. �Reaction time Distance = velocity x

Try an example… � Eg. A car is moving at 50 km/h on dry pavement. Suddenly, 34 m away, a small dog darts into the roadway. Typically the driver takes 1. 5 seconds to react. What is the total reaction distance?

Try an example… � Eg. A car is moving at 50 km/h on dry pavement. Suddenly, 34 m away, a small dog darts into the roadway. Typically the driver takes 1. 5 seconds to react. What is the total breaking distance?

Total Stopping Distance �Therefore, when looking at the length that it takes a car to come to a stop we must look at the reaction time of the driver, as well as the braking distance. �Total Stopping Distance = reaction distance + braking distance

Try an example… � Eg. A car is moving at 50 km/h on dry pavement. Suddenly, 34 m away, a small dog darts into the roadway. Typically the driver takes 1. 5 seconds to react. What is the total stopping distance?