Question

how is it possible to adjust the time when you cross into a diferent time zone

Answer 1

Due to its rotation (Earth's motion around an imaginary axis, which crosses from one pole to the other, towards the West to the East), the Earth has days and nights. As a result, different parts of the Earth's surface have different schedules.

The determination of the time assumes that the Earth is a perfect circle, measuring 360 °, and that the Earth's rotation lasts 24 hours. Therefore, it is concluded that it is the time required for all meridians "intersect" the planet pass at a given moment in front of the sun.

Dividing 360 degrees by the terrestrial sphere 24 hour duration of the rotation movement, resulting 15 degrees. Therefore, every 15 degrees that the Earth rotates, pass one hour - and each of these 24 tracks is called zone.

I have helped you :)

Answer 2

Como é que é possível ajustar o tempo quando você cruzar para um fuso horário diferente
 
Espero ter ajudado!!!(I have helped!!!)

Obs:Eu traduzi a frase.(I translated the phrase.)