The variation of pressure (P) as a function of change in elevation (z) is described by dP = - p g dz Note that the density p is a function of elevation z. The gravity of earth can be assumed to be constant (g 9.81 m/s2). Up to an elevation of about 10,000 m the temperature in the atmosphere near earth's surface can be approximated by = T(z) = 15-0.00651 z with z in [m] and T in [C] Using the ideal gas assumption for air (R = 287 J/kg-K), determine the pressure at an elevation of 3,000 m if P = 101 kPa at z = 0 m.