Stopping distances are a favourite part of the theory test, but they’re not easy to remember. That’s unless you know a special trick… which we’ll reveal here.
It takes a bit of maths, but bear with us. All you need to do is multiply the speed by intervals of 0.5, starting with 2. That’ll give you the stopping distance in feet, which is acceptable for the theory test. For example…
20mph x 2 = 40 feet
30mph x 2.5 = 75 feet
40mph x 3 = 120 feet
50mph x 3.5 = 175 feet
60mph x 4 = 240 feet
70mph x 4.5 = 315 feet
There are 3.3 feet in a metre – so divide the distance in feet by 3.3 to get the stopping distance in metres. You’ll need a calculator for that, but it shouldn’t be necessary for the theory test.
Example:
Question: What is the overall stopping distance at 50mph?
Answer: Factor for 50mph is 3.5 and so overall stopping distance at 50mph is 50 x 3.5 = 175 feet.
Thinking Distance
The thinking distance (in feet) is the same as the speed (in mph).
Example:
Question: What is the thinking distance at 50mph?
Answer: Thinking distance at 50mph is 50 feet.
Braking Distance
The braking distance is the overall stopping distance minus the thinking distance.
Example:
Question: What is the braking distance at 50mph?
Answer: Overall stopping distance at 50mph is 175 feet (see above).
Thinking distance at 50mph is 50 feet (see above). So braking distance is 175 - 50 = 125 feet.