The mach number of the plane which is travelling at supersonic speed is:

CONCEPT:

Supersonic speed:

• Supersonic speed is the speed of an object that exceeds the speed of sound.

​Mach number:

• It is defined as the ratio of the speed of the object to the speed of sound.

​\(⇒ M=\frac{u}{v}\)

Where M = Mach number, u = speed of the object, and v = speed of sound

EXPLANATION:

• The Mach number is given as,

\(⇒ M=\frac{u}{v}\)     -----(1)

Where M = Mach number, u = speed of the object, and v = speed of sound

• For the supersonic speed, the speed of the plane will be more than the speed of sound.

⇒ u > v     -----(2)

Bu equation 1 and equation 2,

⇒ M > 1

• Hence, option 2 is correct.