SortStack #1891 — 2031-08-13

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 king penguin waddling on land 2.8 km/h

   A penguin's waddle is surprisingly efficient, storing and releasing energy with each side-to-side rock.

3. An Olympic swimmer at full speed 9.3 km/h

   Top swimmers shave their bodies to cut drag, trimming fractions of a second that can decide a gold medal.

4. An electric scooter 25 km/h

   Shared e-scooters exploded across cities in just a few years, becoming a common sight on sidewalks worldwide.

5. A polar bear running 40 km/h

   A polar bear's skin is actually black under its clear, hollow fur, helping it soak up the Arctic sun.

6. A 5.56mm rifle bullet 3.1K km/h

   Small, fast rifle rounds tumble on impact, transferring energy in ways a slower, heavier bullet would not.

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