Mach (20°C, 1 atm) to Centimeter 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.

Centimeter per second measures distance in centimeters traveled in one second. Common for small-scale movements and flows.

1 cm/s = 0.01 m/s = 0.036 km/h = 0.6 m/min.

To m/s: ÷ 100. To km/h: × 0.036. To mm/s: × 10.

Stream/river surface flow (10–200 cm/s), blood flow velocity in arteries (10–100 cm/s), small machine movements, and insect flight speeds.

Housefly speed: ~200 cm/s. Blood in aorta: ~40 cm/s. Small stream flow: 30–100 cm/s. Ant running: 1–3 cm/s.

Confusing cm/s with m/s — off by a factor of 100. Mixing up with mm/s.

100 cm/s = 1 m/s. Good for water flow, blood flow, and small animal speeds. Divide by 100 to get m/s.