Mach (20°C, 1 atm) to Meter per Hour

Mach number is the ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 at 20°C, 1 atm equals approximately 343.6 m/s (1,235 km/h).

Mach = velocity ÷ speed_of_sound. At 20°C: Mach 1 = 343.6 m/s. Speed of sound = √(γRT/M) where γ = heat capacity ratio.

To m/s (at 20°C): × 343.6. To km/h (at 20°C): × 1,237. Note: changes with altitude and temperature.

Fighter jets (Mach 1.5–2.5), commercial aircraft (Mach 0.8–0.85), space shuttle reentry (Mach 25), and missile speeds.

Concorde: Mach 2.04. SR-71 Blackbird: Mach 3.3. X-15: Mach 6.7. Meteorites enter at Mach 50+. Subsonic <1, supersonic >1, hypersonic >5.

Thinking Mach is constant — it varies with temperature/altitude. At 30,000 ft, Mach 1 ≈ 295 m/s (colder air = slower sound).

Mach 1 = speed of sound. Below Mach 1 = subsonic. Mach 1–5 = supersonic. Above Mach 5 = hypersonic. It's a ratio, not a fixed speed.

Meter per hour measures the distance in meters traveled over the course of one hour. It's a very slow speed unit used for measuring gradual processes.

1 m/h = 1/3600 m/s = 0.000278 m/s. Very small speed unit for very slow processes.

To m/s: ÷ 3,600. To km/h: ÷ 1,000. To ft/h: × 3.281.

Glacier movement (typically 10–200 m/h in fast glaciers), hair growth (0.0001 m/h), slow industrial processes, and scientific experiments.

Average glacier: 10–100 m/h. Tectonic plate movement: ~0.005 m/h. Bamboo (fastest growing plant): up to 0.091 m/h.

Confusing m/h with m/s — m/h is 3,600 times slower. Using it for normal speeds instead of km/h or m/s.

Remember: 1,000 m/h = 1 km/h. Useful for very slow processes. Think glaciers, not cars.