Describing Behaviour

Some words have certain meanings in colloquial English but have very different, definite meanings in science and engineering.

There are a number of words that precisely describe a certain aspect of the behaviour of materials and you must learn these definitions along with a good example of a material which shows this property well.

Stiffness	Resistance to deformation under the action of an applied force, e.g. in tension. Steel is a stiff material.
Strength	Resistance to breaking under the action of an applied force. Steel is also a very strong material.
Toughness	Resistance to cracking. Leather is tough.
Brittleness	Prone to cracking. The opposite of tough. Glass and ceramics are brittle.
Ductility	Ability to be drawn into a wire. Copper and lead are ductile.
Hardness	Resistance to indentation or scratching. Diamond is the hardest known material.