Approximately, how does the braking distance of a moped increase if its speed doubles?
Show the correct answer
Correct answer
C. Four times.
Explanation
The question is about how the braking distance of a moped changes when the speed is doubled. It increases approximately four times - answer C.
The energy of motion, which the brakes must turn into heat, grows with the square of speed. Twice as fast therefore means four times more energy, and with the same braking force - a braking distance roughly four times longer. Twice (answer A) and three times (answer B) are values that are too low and would make you less alert. On top of this comes the distance travelled during your reaction time, which grows in proportion to speed. Example: if at 20 km/h you stop with the brakes in about 2-3 metres, then at 40 km/h you already need about 8-12 m. That is why a few km/h more near a school or a crossing makes a huge difference.
Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)