Mach (20°C, 1 atm) to Yard per Second

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 second measures distance in yards traveled in one second.

1 yd/s = 0.9144 m/s = 3.29 km/h = 2.045 mph = 3 ft/s.

To ft/s: × 3. To m/s: × 0.9144. To mph: × 2.045.

Sprint speeds in track and field (10–12 yd/s for elite sprinters), projectile velocities, and some fluid flow measurements.

Usain Bolt peak: ~13.5 yd/s. NFL wide receiver sprint: ~11 yd/s. Baseball thrown: ~40–45 yd/s.

Confusing with ft/s — yd/s is 3× faster. Mixing up with mph.

1 yd/s = 3 ft/s = 0.9144 m/s. Multiply by ~2 to get approximate mph.