Statics is the action of one body on another. A force is either a push or a pull. A force tends to move a body in the direction of its action. The action of a force is characterized by its magnitude, by the direction of its action, and by its point of application. Thus, force is a vector quantity, because its effect depends on the direction as well as on the magnitude of the action. Forces are classified as either contact or body forces. A contact force is produced by direct physical contact; an example is the force exerted on a
Sound intensity differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone. The rate at which sound energy passes through a unit area held perpendicular to the direction of propagation of sound waves is called intensity of sound. Sound intensity, denoted I, is defined by where Both I and v are vectors, which means that both have a "direction" as well as a magnitude. The direction of sound intensity is the average direction in which energy is flowing. The average sound intensity during time "T" is given by For a "spherical" sound wave, the intensity