The speed of sound in air (in m/s) depends on temperature according to the approximate expression v = 331.5 + 0.607TC where TC is the Celsius temperature. In dry air the temperature decreases about 1°C for every 150 m rise in altitude.
(a) Assuming this change is constant up to an altitude of 9 000 m, how long will it take the sound from an airplane flying at 9 000 m to reach the ground on a day when the ground temperature is 30°C?
(b) What If? Compare this to the time interval required if the air were a constant 30°C. Which time interval is longer?