| Elastic energy: | (english) The energy stored in deformed elastic material (e.g., a watch spring). Elastic energy equals where k is the stiffness, and is the associated deflection. Elastic energy is sometimes called elastic potential energy because it can be recovered when the object returns to its original shape; see potential energy. |
| Energy: | (english) A property of a body related to its ability to move a force through a distance opposite the force's direction; energy is the product of the magnitude of the force times the distance. Energy may take several forms: see kinetic energy, potential energy, and elastic energy. |
| Equilibrium: | (english) An object is in equilibrium if the resultant of the system of forces acting on it has zero magnitude. See static equilibrium and dynamic equilibrium. |
| Flexibility: | (english) Flexibility is the inverse of stiffness. When a force is applied to a structure, there is a displacement in the direction of the force; flexibility is the ratio of the displacement divided by the force. High flexibility means that a small load produces a large displacement. |
| Force: | (english) A directed interaction between two objects that tends to change the momentum of both.Since a force has both direction and magnitude, it can be expressed as a vector |
| Inelastic: | (english) Not surprisingly, the opposite of elastic. A deformation of a structure or material under load is described as inelastic when the deformation remains after the load is removed. The term plastic is often used with the same meaning. |
| Inertial Force: | (english) A fictitious force used for convenience in visualizing the effects of forces on bodies in motion. For an accelerating body, the inertial force is considered as a body force whose resultant acts at the object's center of gravity in a direction opposite the acceleration. The magnitude of the force is the mass of the object times the magnitude of the acceleration. |
| Linear: | (english) A structure is said to behave linearly when its the deformation response is directly proportional to the loading (i.e. doubling the load doubles the displacement response). For a material, linear means that the stress is directly proportional to the strain. |
| Load: | (english) An external force. The term load is sometimes used to describe more general actions such as temperature differentials or movements such as foundation settlements. |
| Moment: | (english) The resultant of a system of forces causing rotation without translation. A moment can be expressed as a couple. |