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Braking distance refers to the distance a vehicle will travel from the point when its brakes are fully applied to when it comes to a complete stop. It is primarily affected by the original speed of the vehicle and the coefficient of friction between the tires and the road surface, [Note 1] and negligibly by the tires' rolling resistance and vehicle's air drag.
d MT = braking distance, m (ft) V = design speed, km/h (mph) a = deceleration rate, m/s 2 (ft/s 2) Actual braking distances are affected by the vehicle type and condition, the incline of the road, the available traction, and numerous other factors. A deceleration rate of 3.4 m/s 2 (11.2 ft/s 2) is used to determine stopping sight distance. [6]
Brakes convert the kinetic energy of a vehicle into heat over the distance traveled by said vehicle. Thus, we can find the brake force of a vehicle through the formula: [ 1 ] F b = m v i 2 2 d {\displaystyle F_{b}={mv_{i}^{2} \over 2d}}
The brake balance or brake bias of a vehicle is the distribution of brake force at the front and rear tires, and may be given as the percentage distributed to the front brakes (e.g. 52%) [1] or as the ratio of front and rear percentages (e.g. 52/48). [2]
The braking a is from an initial speed u to a final speed v, over a length of time t. The equation u - v = at implies that the greater the acceleration the shorter the time needed to change speed. The stopping distance s is also shortest when acceleration a is at the highest possible value compatible with road conditions: the equation s = ut ...
The values in the table don't match the equation. I don't know if the equation or the table is correct but if the formula is correct the higher values of speed should have stopping distances in the thousands. 69.54.143.208 06:01, 15 March 2007 (UTC)Theodore . I have removed both the table and the formula.
Since kinetic energy increases quadratically with velocity (= /), an object moving at 10 m/s has 100 times as much energy as one of the same mass moving at 1 m/s, and consequently the theoretical braking distance, when braking at the traction limit, is up to 100 times as long. In practice, fast vehicles usually have significant air drag, and ...
The two-second rule is useful as it can be applied to any speed. Drivers can find it difficult to estimate the correct distance from the car in front, let alone remember the stopping distances that are required for a given speed, or to compute the equation on the fly. The two-second rule provides a simpler way of perceiving the distance.