Question

Calculate the pressure of air at a height of 3500m from sea level where pressure and temperature of air are 10 N/cm^2 and 25℃ respectively. The temperature lapse rate is given as 0.0065 ℃ /m. Take density of air at sea level equal to 1.2 kg/m^3.

(a) 19.7 N/cm^2

(b) 9.85 N/cm^2

(c) 4.93 N/cm^2

(d) 6.24 N/cm^2

The question was posed to me in examination.

I need to ask this question from Pressure at a Point in Compressible Fluid topic in portion Pressure and Its Measurement of Fluid Mechanics

Answer 1

Right option is (b) 9.85 N/cm^2

To elaborate: pressure=p * (1-(k-1/k)*g*h*density/p)^k/(k-1)

                                   =9.85 N/cm^2

Here, Lapse rate= -g/R*(k/k-1).