Mach number

Definition

Mach number is the ratio of the speed of an object to the speed of sound in the surrounding medium. It is a dimensionless quantity used in fluid dynamics and aerodynamics.

5 Must Know Facts For Your Next Test

1. A Mach number less than 1 indicates subsonic speeds, while a Mach number greater than 1 indicates supersonic speeds.
2. The speed of sound varies with temperature and medium, affecting the Mach number calculation.
3. Shock waves form when an object travels at or above Mach 1, causing sudden changes in pressure and temperature.
4. Mach numbers are critical in designing aircraft and spacecraft to ensure structural integrity at high speeds.
5. The term 'Mach' is named after Ernst Mach, an Austrian physicist who studied shock waves and supersonic motion.

Review Questions

• What does a Mach number greater than 1 signify?
• How does temperature affect the calculation of the Mach number?
• Why are Mach numbers important in aerospace engineering?

Related terms

Supersonic:

A speed that is greater than the speed of sound in a given medium, corresponding to a Mach number greater than 1.

Subsonic: A speed that is less than the speed of sound in a given medium, corresponding to a Mach number less than 1.

Shock Wave:

\text{A type of propagating disturbance that moves faster than the local speed of sound, creating abrupt changes in pressure, temperature, and density.}