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
Introduction to the mathematics of general relativity line, which is a one-dimensional object. A tensor extends this concept to additional dimensions. A two-dimensional tensor would be called a second-order tensor. This can be viewed as a set of related vectors, moving in multiple directions on a plane. Vectors are fundamental in the physical sciences. They can be used to represent any quantity that has both a magnitude and direction, such as velocity, the magnitude of which is speed. For example, the velocity "5 meters per second upward" could be represented by the vector (in 2 dimensions with the positive axis as 'up'). Another quantity represented by a