Z-line can refer to: 1  the borders that separate and link sarcomeres within a skeletal muscle. 2  a ban on a user's IP address for the purposes of blocking their access to Internet Relay Chat.3  the gastroesophageal junction that joins the esophagus to the stomach. 4  Z, a New York City Subway service.-line can refer to: 1  the borders that separate and link sarcomeres within a skeletal muscle. 2  a ban on a user's IP address for the purposes of blocking their access to Internet Relay Chat.
If we take another look at the Mach 1 vs. altitude tables already discussed, we see that the speed of sound at 30,000 ft is 678.2 miles per hour. All we have to do is multiply this value by 3 to determine the speed of a vehicle traveling Mach 3 at 30,000 ft in miles per hour. The answer is 2,035 mph.ach number: Mach number is a quantity that defines how quickly a vehicle travels with respect to the speed of sound. The Mach number (M) is simply the ratio of the vehicle's velocity (V) divided by the speed of sound at that altitude (a).
SPEED OF SOUND AT DIFFERENT ALTITUDES. Mach 1.0 is the speed of sound in air, so a plane flying Mach 2.0 is flying twice as fast as the speed of sound. The speed of sound is not a constant, but depends on altitude (or actually the temperature at that altitude). A plane flying Mach 1.0 at sea level is flying about 1225 km/h (661 Knots, 761 mph), a plane flying Mach 1.0 at 30000 ft is flying 1091 km/h (589 knots, 678 mph) etc. Speeds below Mach 1 are called subsonic, between Mach 0.8-1.2 Transonic and above Mach 1.2 Supersonic.