If you are driving at 100 km/h and increase your speed to 110 km/h, how much time do you gain per 10 km?
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Driving Licence Book (19th Edition, page 84):
“If you increase your average speed by 10 km/h, the time gain per 10 km will be:
– approximately 1 minute at speeds under 90 km/h
– approximately ½ minute at speeds over 90 km/h”
In all likelihood, you will not need to know the following mathematical calculations for the real test. It is enough to know that the time gain is minimal.
Colour codes for the figures (easier to keep track of them) | |
Original speed | 100 km/h |
New speed | 110 km/h |
Minutes per hour (since the speed is km/h, kilometres per hour) | 60 minutes |
Number of kilometres | 10 km |
We first calculate how many minutes it takes to travel 1 km at both speeds:
It is therefore takes slightly less time with the higher speed. The difference is:
However, the question is how much time you gain per 10 km, not per km. Therefore, recalculate the time gain per 10 km:
Now it is really done. It is however easier to understand if the answer is recalculated to seconds:
Colour codes for the figures (easier to keep track of them) | |
Original speed | 100 km/h |
New speed | 110 km/h |
Distance | 10 km = 10,000 metres |
Fixed conversion rate km/h to m/s | 3.6 times |
Formula for calculation of time:
For the formula to work requires us to use metres instead of 10 km and metres per second (m/s) instead of kilometres an hour (km/h). The speeds are therefore recalculated to m/s:
Only now can we use the formula Distance / speed = time:
We can then work out the time difference between both speeds:
This is an example of one of the driving theory questions at Körtkortonline.se (also in theory tests in Arabic).
There is also a driving licence book online (2022).
More examples of theory questions:
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