The Braking Distance calculator computes the distance to stop a vehicle based on the initial velocity (vi) and the a braking coefficient (μ).
INSTRUCTIONS: Choose units and enter the following:
- (vi) Initial velocity
- (μ) Braking Coefficient
Braking Distance (BD): The calculator returns the distance (BD) in meters. However this can be automatically converted to other distance units via the pull-down menu.
The Math / Science
The Braking distance refers to the distance a vehicle will travel 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 roads surface, and negligibly by the tires rolling resistance and vehicle's air drag. The type of brake system in use only affects trucks and large mass vehicles, which cannot supply enough force to match the static frictional force.
The breaking distance is one of two components of total stopping distance. The following formula is used to calculate the braking distance:
`BD=v_i^2/(2*mu*g)`
where:
- vi = initial velocity
- μ = friction factor
- g = acceleration due to gravity on earth
Braking Coefficient
The Braking Coefficient is a coefficient of kinetic friction. For accident reconstruction on dry surfaces, a value of 0.7 is often used. This is the default value in this calculator. A modern car with computerized anti-skid brakes may have a friction coefficient of 0.9 - or even far exceed 1.0 with sticky tires.
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- Braking Distance: Computes the distance to stop a vehicle based on the initial velocity (vi) and the a braking coefficient (μ).
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References
Formula and definition are from Wikipedia (https://en.wikipedia.org/wiki/Braking_distance).