| density | mass per unit volume |
| pressure | the normal (or perpendicular) force acting per unit cross-sectional area |
| Archimedes' principle | the upthrust acting on a body is equal to the weight of the liquid or gas that it displaces |
| compressive | describes a force that squeezes and shortens an object |
| tensile | associated with tension or pulling; for example, a tensile force |
| extension | the increase in the length of a material from its original length |
| spring constant | the force per unit extension for a spring; unit is N/m |
| Hooke's law | provided the elastic limit is not exceeded, the extension of an object is proportional to the applied force (load). |
| elastic deformation | an object that returns to its initial length when the force is removed has deformed elastically |
| plastic deformation | an object that does not return to its initial length when the force is removed is deformed permanently - it has deformed plastically |
| limit of proportionality | the point beyond which extension (of a spring) is no longer proportional to the force |
| elastic limit | the value of stress beyond which an object (such as a spring) will not return to its original dimensions |
| strain | extension per unit length |
| stress | force per unit cross-sectional area that acts at right angkes to a surface |
| Young modulus (of a material) | the stress in the material divided by the strain |
| elastic potential energy | energy stored in a body due to a change in its shape |
| strain energy | energy stored in a body due to a change in its shape |
| work done | the product of the force and the distance moved in the direction of the force; the area under a force extension graph |
