Stopping Distance Calculator
Calculate the braking distance from speed and road friction.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Enter the vehicle speed and select the unit. Enter the friction coefficient for the road conditions. The calculator computes the minimum braking distance assuming immediate brake application on a flat surface.
About Stopping Distance
Stopping distance is the distance a vehicle travels from the moment brakes are fully applied until it stops. It depends on the square of the initial speed and inversely on the friction coefficient and gravity. This calculation uses energy conservation: kinetic energy (0.5mv2) equals work done by friction (mu x mg x d). Understanding stopping distance is critical for road safety, speed limit design, and driver education. Wet or icy conditions dramatically increase stopping distance.
Frequently Asked Questions
How is stopping distance calculated?
Stopping (braking) distance equals v2 / (2 x mu x g), where v is speed, mu is the friction coefficient, and g is gravitational acceleration. This assumes maximum braking on a flat road.
What is a typical friction coefficient for dry road?
Dry asphalt with good tires: 0.7-0.8. Wet road: 0.3-0.5. Ice: 0.1-0.2. These values significantly affect stopping distance.
Why does stopping distance increase with the square of speed?
Kinetic energy is proportional to v2, and all that energy must be dissipated by friction to stop the vehicle. Doubling speed quadruples the stopping distance.