Stress (mechanics)

In continuum mechanics, stress is a pheesical quantity that expresses the internal forces that neebourin pairticles o a conteenous material exert on ilk ither, while streen is the meisur o the deformation o the material. For ensaumple, when a solit vertical baur is supportin a wecht, each pairticle in the baur pushes on the pairticles immediately ablo it.

Biggit-in strain, inside the plastic protractor, developed bi the stress o the shape o the protractor, is revealed bi the effect o polarised licht.