Informally, a tangle of string is called a knot, although in mathematics a knot is a loop, having no beginning and no end, and is hence an embedding of a simple circle into three dimensional space. Knot theory asks whether one embedding can be smoothly transformed into another, and is therefore an area of topology.

Alternatively, a speed of one nautical mile per hour is called a "knot". In trying to estimate one's position by use of dead reckoning, speeds were estimated by throwing a lump of wood (the log) into the water, letting the string run out, and counting how many knots passed through the fingers in a given time. Originally the knots were 7 fathoms (42 feet) apart and the timer was 30 seconds, but this was later changed to 47'3" and 28 seconds respectively.

Exercise: What two speeds do these settings correspond to?

Last change to this page
Full Page history
Links to this page
 Edit this page
  (with sufficient authority)
Change password
 Recent changes
All pages
Search