The atmospheric pressure at sea level is 760mm of mercury. At what height it will be 740mm of mercury? Take the density of air 1.293kg/m3 constant upto height about 1 km.
Given, atmospheric pressure, P1= 760 mm of Hg
Atmospheric pressure, P2 = 740 mm of Hg
Density of air,
Let the height at which the atmospheric pressure is decreased be 'h'.
Now, Pressure due to h height of air = Pressure due to 2 cm or 0.02 m of mercury.
1.293 x g x h = 13600 x g x 0.02
h = 210 m, is the height at which the atmospheric pressure will decrease.