Convert Furlong per Fortnight to Mach 20
Convert Furlong per Fortnight (fur/fn) to Mach 20 (Ma20) instantly and accurately.
Conversion Formula
Ma20 = fur/fn × 2.443644007e-8
About Furlong per Fortnight
A furlong per fortnight (fur/fn) is a deliberately archaic unit equal to exactly 201.168 ÷ 1,209,600 m/s ≈ 1.663 × 10⁻⁴ m/s - just slightly faster than a garden snail at full creep. One furlong (one-eighth of a mile = 201.168 m) and one fortnight (14 days = 1,209,600 s) are both perfectly legitimate historical measures, but their combination is cherished in physics teaching as a cautionary example of needlessly exotic unit choices. Expressing kinetic energy in kg·fur²/fn² or force in kg·fur/fn² illustrates instantly why the SI was universally adopted. The unit appears in satirical physics papers, recreational mathematics columns, and Terry Pratchett's Discworld novels as the native velocity unit of magical phenomena. The speed of light expressed in furlongs per fortnight is approximately 1.803 × 10¹² fur/fn. Snails travel at roughly 0.5-1 fur/fn; strong tidal rip currents reach 100-200 fur/fn. 1 fur/fn ≈ 1.663 × 10⁻⁴ m/s ≈ 0.599 km/h ≈ 0.372 mph.
About Mach 20
Mach 20 ≈ 6,805.8 m/s (24,501 km/h) at ISA sea level - the peak heating regime of ballistic re-entry. Shock layer temperature exceeds 10,000 K; plasma sheath causes radio blackout. Space Shuttle decelerated through Mach 20 at ~75-80 km altitude; Apollo CM hit the atmosphere at ~Mach 36; ICBM warheads re-enter at Mach 18-24. DARPA HTV-2 reached Mach 20 in 2011. 1 Mach 20 = 6,805.8 m/s.
Quick Reference Table
| Furlong per Fortnight (fur/fn) | Mach 20 (Ma20) |
|---|---|
| 1 fur/fn | 2.444 × 10-8 Ma20 |
| 2 fur/fn | 4.887 × 10-8 Ma20 |
| 5 fur/fn | 1.222 × 10-7 Ma20 |
| 10 fur/fn | 2.444 × 10-7 Ma20 |
| 25 fur/fn | 6.109 × 10-7 Ma20 |
| 50 fur/fn | 1.222 × 10-6 Ma20 |
| 100 fur/fn | 2.444 × 10-6 Ma20 |