What is a ‘stress fracture’?
What is a ‘muscle strain’?
What exactly do the words ‘stress’ and ‘strain’ mean?
We often think of the words going together, but they mean very different things.
STRESS
Stress means force – (like the word ‘press’)- a push or a pull.
An object feeling stress is feeling a strong force applied to it.
A ‘stress fracture’ is a fracture caused by a bone being used normally but having to bear too strong a force.
What do the following mean?
1) The material can take high stresses without deforming.
2) The material snapped at low stresses.
STRAIN
Strain means stretching – (like ‘train’) – or squashing.
An object feeling strain is an object being stretched (or squashed).
A ‘muscle strain’ is a muscle damaged by being stretched too far.
What do the following means?
3) This material breaks when strained.
4) A small force caused a large strain of the material.
But, even though they mean different things, stress and strain do go together.
Objects subject to large forces (large stresses) tend to squash or stretch (strain).
Stress causes strain. Force causes stretching.
5) Can you think of a material that can take very large stresses but with hardly any strain at all?
6) Can you think of a material that only needs very small stresses to be subject to a great deal of strain?
