Braking distance
Encyclopedia
Braking distance refers to the distance a vehicle will travel from the point where its brakes are fully applied to when it comes to a complete stop. It is affected by the original speed of the vehicle, the type of brake system in use, the reaction time of the driver/rider and the coefficient of friction between its tires
and the road surface.
.
The kinetic energy is given by the formula:
where is the vehicle's mass and is its speed.
The work done by braking is given by:
where is the coefficient of friction between the road surface and the tires, is the gravity of Earth, and is the distance travelled.
The braking distance (which is commonly measured as the skid length) given an initial driving speed is then found by putting , from which it follows that
The maximum speed given an available braking distance is given by:
Note that these theoretical formulas do not take account of the driver's reaction time.
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
and the road surface.
Energy equation
The theoretical braking distance can be found by determining the work required to dissipate the vehicle's kinetic energyKinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
.
The kinetic energy is given by the formula:
- ,
where is the vehicle's mass and is its speed.
The work done by braking is given by:
- ,
where is the coefficient of friction between the road surface and the tires, is the gravity of Earth, and is the distance travelled.
The braking distance (which is commonly measured as the skid length) given an initial driving speed is then found by putting , from which it follows that
- .
The maximum speed given an available braking distance is given by:
- .
Note that these theoretical formulas do not take account of the driver's reaction time.