This is a Thermodynamic question Find total mass of an air i

This is a Thermodynamic question.

Find total mass of an air in a hall, which has a 50*50*12 in^3 volume, built 7000ft above sea level.

Solution

at 7000 ft above sea level

P = 78.19 kPa T=274 K (from table ) we can calculate pressure by P = P0 - rho*g*h also where P0- atmoshpheric pressure

PV = mRT

m = PV/RT

= 78.19*50*50*12*0.0254^3 / 0.287*274 = 0.48888 kg