SortStack #2118 — 2032-03-27

By duration · Order from shortest to longest.

1. A lightning flash from start to finish 198 ms

   What looks like one bolt is usually several return strokes in a row, heating the air to around 30,000°C — five times hotter than the Sun's surface.

2. One swing of a grandfather clock's pendulum 1 sec

   A pendulum about one metre long swings in almost exactly one second — a coincidence so neat it was once proposed as the definition of the metre.

3. Usain Bolt's 100 m world record run 9.6 sec

   Bolt ran 9.58 in Berlin 2009, hitting a top speed of 44.7 km/h — faster than the speed limit on many city streets.

4. A proper hand wash, by WHO guidelines 19.8 sec

   The recommended scrub lasts about as long as singing 'Happy Birthday' twice — most people manage barely a third of it.

5. The Isner-Mahut match, the longest in tennis history 11.1 h

   The 2010 Wimbledon first-rounder stretched over three days with a 70-68 final set — the scoreboard wasn't programmed to go that high and broke.

6. The Islamic holy month of Ramadan 29.5 days

   Because it follows the lunar calendar, Ramadan drifts about 11 days earlier each year — cycling through every season over 33 years.

← All puzzles · Play today’s SortStack