Mach (20°C, 1 atm) to Yard 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.

Yard per hour measures distance in yards traveled over one hour. Rarely used except in specialized contexts.

1 yd/h = 0.000254 m/s = 0.0009144 km/h = 0.9144 m/h.

To yd/min: ÷ 60. To ft/h: × 3. To m/h: × 0.9144.

No common modern applications. Might appear in some historical documents.

No notable facts — too rarely used.

Even existing is a mistake — use m/h, ft/h, or mph instead.

1,760 yd/h = 1 mph. Extremely uncommon. Better to use other units.