In what way does doubling of the motorcycle speed affect the braking distance?
Show the correct answer
Correct answer
B. It quadrouples the braking distance.
Explanation
The question is about the effect of speed on braking distance. Doubling the speed of a motorcycle makes the braking distance four times longer - answer B.
The Road Traffic Act tells you to drive at a speed that ensures control of the vehicle, taking into account the traffic conditions, and it is the braking distance that shows why. The energy of motion grows with the square of speed: at twice the speed, a motorcycle has four times as much energy, and the brakes, with the same braking force, need a four times longer distance to get rid of it. Example: from 50 km/h on dry asphalt you stop in about 15 m, from 100 km/h - in about 60 m, and on top of that comes the reaction distance, nearly 30 m at 100 km/h. Answer A confuses a linear relationship with a quadratic one, and answer C is obviously false. This rule also works the other way round: slowing down from 60 to 50 km/h in town shortens the braking distance by almost a third - often by as much as you need to stop before a pedestrian.
Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)