... axes¹

Consider a blob of modeling clay--you can deform it by placing between your thumbs and one opposed finger; you can deform it by simultaneously squeezing with two sets of opposable digits; you can ``smear'' it by pushing and pulling in opposite directions. These are examples of uniaxial, biaxial, and shear stress.

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... shape.²

It is unfortunate that the words of these two related physical quantities, stress and strain, sound so similar. Strain measures the change in geometry of a body and stress measures the forces that squeeze or pull on a body. Stress is the press; Strain is the gain.

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