Question

The mean sea- level pressure of the atmosphere decreases by half at the altitude of ? A) 6 Km. B) 8 Km. C) 10 Km. D) 12 Km.

Answer 1

A

Explanation:

The atmospheric pressure depends by the weight of the air over us. air has a density of about `0,9 (kg)/m^3` that decreases with altitude starting from about `1,2 (kg)/m^3` at ground level to `0,6 (kg)/m^3` at about 6000 m). therefore an height of air of 6000 m wiht a m^2 of surface weighs about `P= d xx V xx g = 0,9(kg)/m^3 xx 6000 m^3 xx 10 m/s^2= 54000 N` that give on a surface of a m^2 a pressure of 54000 Pascal , about 0,5 atm.
1 atm is 101325 Pa