In what way does doubling of the speed of a passenger car influence the braking distance?
Show the correct answer
Correct answer
B. It quadruples the braking distance.
Explanation
Doubling your speed makes the braking distance four times longer - answer B. The braking distance does not grow in proportion to speed (A), and it certainly does not stay the same (C).
The energy of a moving vehicle grows with the square of its speed: a car travelling twice as fast has four times as much energy, which the brakes must turn into heat, so they need a section four times longer to do it. If from 50 km/h you stop on dry asphalt after about 14 m, then from 100 km/h you need about 56 m of braking alone, not counting the distance travelled during your reaction time. That is why the Road Traffic Act requires you to drive at a speed that allows you to keep control of the vehicle and to keep a distance that allows you to avoid a collision if the vehicle in front brakes.
Legal basis: Art. 19 para. 1 and para. 2 point 3 of the Road Traffic Act (Prawo o ruchu drogowym)