Braking distance
The distance a vehicle travels from the moment the brakes are applied until it comes to a complete stop. It depends on the initial velocity and the magnitude of deceleration (friction and air resistance). Braking distance increases as the square of initial velocity: s ∝ v₀².
Formula
s = v₀² / (2a)
Real World
UK Highway Code data shows a car braking from 70 mph needs 75 m to stop — quadruple the 18 m needed from 35 mph, illustrating the v² relationship.
Exam Focus
When speed doubles, braking distance quadruples — state this explicitly in 'explain' questions rather than just quoting the formula.
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