SortStack #1562 — 2030-09-18

By speed · Order from slowest to fastest.

1. The growth of human hair 175.3 mm/year

   Scalp hair grows roughly 1.25 centimetres a month, so a single strand reaching your shoulders is years old.

2. An arrow loosed from a bow 230 km/h

   A modern compound bow uses pulleys to store huge energy, launching an arrow with deadly accuracy.

3. A record tennis serve 270 km/h

   The fastest serves leave the racket so quickly the returner must react before the ball has even crossed the net.

4. The speed of sound at sea level 1.2K km/h

   Sound travels faster in warm air than cold, so a thunderclap's timing shifts slightly with the weather.

5. A .220 Swift rifle bullet 4.4K km/h

   Among the fastest commercial rifle rounds, it leaves the barrel so quickly the bullet can melt slightly in flight.

6. The International Space Station in orbit 28K km/h

   The station circles Earth so fast its crew sees about 16 sunrises and sunsets every single day.

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