Introduction
   What do knots have to do with physical science? Everything! In this unit you will learn some of the history behind specific knots. You'll learn something about how the structure of knots illustrates physics concepts and much, much more.
   Later on, we will use the specific knots you are learning in the creation of bridges, towers and catapults. So learn well, least ye stumble!

Terminology
  (1) Tensile Strentgth: Maximum load that a material can support without fracture when being stretched, divided by the original cross-sectional area of the material. Tensile strengths have dimensions of force per unit area and in the English system of measurement are commonly expressed in units of
pounds per square inch, often abbreviated to psi. When stresses less than the tensile strength
are removed, a material returns either completely or partially to its original shape and size. As
the stress reaches the value of the tensile strength, however, a material, if ductile, that has
already begun to flow plastically rapidly forms a constricted region called a neck, where it then
fractures. (E. Brittanica)

(2) Knots reduce the effective tensile strength of a rope by increasing shear at the knot. A bend in a rope also increases shear, thus pulleys are often used to make bends less extreme.
 
 

Our Knots
 

The double half-hitch	The figure 8 ( The whole family)	The double fisherman's ( barrel) knot
The clove hitch	The tautline hitch	Fishermans knot
The bowline	The truckers hitch	Prussik knot with history
Square knot		The sheet bend

Resources
The Ultimate Web Knot Source
Some animated instructions
Scouting Knot Page
Good illustrations
 Tie a Necktie
Moebius strip
The Mathematics of Knots
Knot Theory - math
The sling - an ancient weapon
Criteria
   To pass this unit you will have to tie all 10 knots in less than 5 minutes. There will be no quiz on this unit - either you can or you can't.

Bonus opportunity - On quiz day there will be a bonus for the five fastest times.