Theory Mastery

Reactieseconde gemiddeld 1 seconde

The reaction second lasts on average 1 second — the time between 'I must brake' and actually pressing the brake pedal. The reaction second is a time (1 second on average), not a distance: it is the period between the moment you perceive the hazard and the moment you actually press the brake.

Source: Speed, distance & stopping distance · checked 2026-10-23

How the exam asks it

At night on the N36 near Vriezenveen you are driving 100 km/h. What is your reaction distance per the book's rule of thumb?

  1. 27.50 m
  2. 1 second
  3. Practically 0 m, since it's negligible
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Correct answer: 27.50 m

'1 second' is the reaction second (time); the reaction distance (metres) is ((100:2)+10%):2 = 27.50 m

Why learners get this wrong: The reaction second is a distance in metres, just like braking distance.

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Near Den Ham you are driving 40 km/h through a transition into a 30-zone. What is your reaction distance in metres per the book's rule of thumb?

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Correct answer: 11 m

Correct: 11.0 m (±1.5).

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Near Daarle you are driving 130 km/h on a road without a speed limit. What is your reaction distance per the book's rule of thumb?

  1. 35.75 m
  2. 1 second
  3. 84.50 m
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Correct answer: 35.75 m

Why learners get this wrong: The reaction second is a distance in metres, just like braking distance.

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Near Notter you explain: 'Reaction distance grows with speed just as fast as braking distance — both quadratically.'

  1. True
  2. False
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Correct answer: False

Why learners get this wrong: The reaction distance grows quadratically with speed, just like braking distance.

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Near Espelo you are driving 50 km/h on a dry road. A cyclist unexpectedly crosses. About how many metres do you still travel before you start braking?

  1. About 3 metres, almost all of it is braking distance after that
  2. About 1 metre, because a reaction second is one metre
  3. About 14 metres, more than half of your stopping distance
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Correct answer: About 14 metres, more than half of your stopping distance

False — you think the reaction distance is negligible. At 50 km/h you travel about 13.75 m during your reaction time, almost as much as the braking distance of 12.50 m

Why learners get this wrong: The reaction distance is so small that in practice it can be ignored next to the braking distance.

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