The speed of sound in air (in m/s) depends on the temperature according to the approximate expression below, where 7 is the Celsius temperature. In dry air the temperature decreases about 10C for every 150 m rise in altitude. V = 331.5 + 0.607T c (a) Assuming this change is constant up to an altitude of 9000 m, how long will it take the sound from an airplane at 7900 m to reach the ground on a day when the ground temperature is 260C? 25.916 X s b) Compare this to the time interval required if the air were constant at 26C. Which time interval is longer? air at constant temperature air at changing temperature Need Help? Read It