1. (30 points). Consider an aircraft climbing steadily in the Earth's atmo-

sphere with a constant speed of 1100 km/hr. As the aircraft goes to higher

altitudes, the temperature of the air changes approximately linearly with

elevation at a rate of -6.6 °C/km. Assume that the temperature at sea

level is 25 °C.

(a) Compute the Mach number of the aircraft when it reaches an altitude

of 3000 m.

(b) Compute the Mach number of the aircraft when it reaches an altitude

of 15000 m.

(c) How does the Mach number of the aircraft vary with elevation? At

what altitude does the flow around it become sonic?