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
Magnitude (astronomy) from the Sun to the faintest object visible with the Hubble Space Telescope (HST): Under the Vega system for measuring the brightness of astronomical brightness, the star Vega is defined to have an apparent magnitude of zero as measured through all filters, although this is only an approximation e.g. its actual brightness has been measured to be 0.03 in the V (visual) band. The brightest star, Sirius, has a Vega magnitude of −1.46. or −1.5. However, Vega has been found to vary in brightness, and other standards are in common use. One such system is the AB magnitude system, in