Mach - Mach number, how many times the speed of sound a thing is traveling, where the speed of sound is measured in the same medium in which the thing is traveling
In Earth's atmosphere, one or more jet engines can propel a plane from Mach 0 to Mach 3.5. In said atmosphere, one or more ramjets can propel a plane from Mach 3 to Mach 6, and one or multiple scramjets are capable of propelling a plane from Mach 6 to Mach 10 or above.[1]
References 
Edit
- ↑ https://www.youtube.com/watch?v=xpOa3B03gYg - title: "Ramjets and Scramjets Explained - Mach 14 - YouTube"; description: "internal jet air flow with a compressor when beyond Mach 8"; bookmarked: 1490122590; favicon: https://www.youtube.com/yts/img/favicon_144-vflWmzoXw.png; last_charset: UTF-8; note: This webpage contains a video;
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