Speed units are used in km/h or m/s, and the transformation between them is done using the factor 3.6.
- Why 3.6?
The conversion factor used is 3.6 due to the correspondence between the measurement units of space and time, with 1 km = 1000 m and 1 h = 3600 s. See the example of converting 72 km/h to m/s.
We see here that 72 km/h corresponds to 20 m/s, that is, a mobile that, in 1 h, moves 72 km or 20 m every second.
- everyday application
Law No. 9,503 of the Brazilian Traffic Code, in article 252, prohibits, among other things, the use of cell phones while driving. Using a cell phone can distract the driver and lead to serious accidents. Speed measurement units can show this danger.
Imagine that a driver is traveling along an avenue at a constant speed of 72 km/h at the moment he receives a message on his cell phone. If that driver takes only 3 s to read the message, he will travel blind for 60 m! As we saw above, 72 km/h corresponds to 20 m/s, that is, every second, the car moves by 20 m. Thus, 3 s of eye on the cell phone makes the driver move for 60 m without seeing anything on the road, enough space for several unforeseen events to occur.