SortStack #3592 — 2036-04-09

By speed · Order from slowest to fastest.

1. The growth of a cave stalactite 0.1 mm/year

   Most stalactites lengthen by less than a tenth of a millimetre a year, dripping mineral by mineral over millennia.

2. A koala on the run 30 km/h

   Koalas sleep up to 22 hours a day because their eucalyptus diet is so low in energy and mildly toxic.

3. A speeding hovercraft 145 km/h

   A hovercraft floats on a cushion of trapped air, gliding equally well over water, land, ice and mud.

4. A maglev train at record speed 460 km/h

   Maglev trains float on magnets with no wheels, so the only friction left to overcome is the air itself.

5. Concorde at cruising speed 2.2K km/h

   Concorde flew so fast that the friction heated its frame, stretching the whole plane several inches in flight.

6. NASA's X-43 scramjet 11.9K km/h

   The X-43 set an air-breathing speed record by burning fuel in a stream of air rushing through it many times faster than sound.

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