Here's a breakdown:

* Mach number represents the ratio of an object's speed to the speed of sound in the surrounding medium (usually air).

* Mach 1 is the speed of sound, which is approximately 767 miles per hour (1,235 kilometers per hour) at sea level.

* Mach 2 is therefore 1,534 miles per hour (2,470 kilometers per hour).

It's important to note that the speed of sound can vary depending on factors like air temperature and altitude.