The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.

Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.