| 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. |
| External force: | (english) A surface force or body force acting on an object. External forces are sometimes called applied forces. |
| Fixed connection: | (english) In two dimensions, a fixed connection between two members restrains all three degrees of freedom of the connected member with respect to one another. A fixed connection is sometimes called a rigid connection or moment-resisting connection. |
| Fixed support: | (english) In two dimensions, a fixed support restrains three degrees of freedom: two translations and one rotation. |
| 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. |
| Flexure: | (english) Bending deformation, i.e., deformation by increasing curvature. |
| 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 |
| Funicular: | (english) A funicular shape is one similar to that taken by a suspended chain or string subjected to a particular loading. |
| Gravity: | (english) An attractive force between two objects; each object accelerates at a rate equal to the attractive force divided by the object's mass. Objects near the surface of the earth tend to accelerate toward the earth's center at a rate of ; this value is often called the gravitational constant and denoted as g. |