A plane is traveling at Mach 0.980 through air at a temperature of 0°C.What is the plane's speed? (Speed of sound at 0°C is 331 m/s. )
A) 314 m/s
B) 324 m/s
C) 348 m/s
D) Mach number is undefined at 0°C.

Question

Quizplus · Accepted Answer

Mach number is the ratio of the speed of an object to the speed of sound in the same medium. In this question, the plane is traveling at Mach 0.980 and the temperature of the air is 0°C, which means that the speed of sound is 331 m/s. Therefore, the plane's speed is calculated as follows: 
Plane speed = Mach number * speed of sound = 0.980 * 331 = 324.38 m/s. 
The closest option to this answer is B, 324 m/s.

A Plane Is Traveling at Mach 0