Q. In fluid mechanics, Mach number is 1, if the speed of an object is equal to the ______? Answer:
Speed of sound
Notes: Mach number is a ratio of the speed of a body (aircraft) to the speed of sound in the undisturbed medium through which the body is traveling. Mach 1 is equal to the speed of sound (which is 332 m/s or 1195 km/hr. ) An aircraft flying at Mach 2 is flying at twice the speed of sound in air, etc.