text: what is force?   in physics, a force is anything that causes a body with mass to accelerate--intuitively, a push or a pull. the net (or resultant) force is the sum of all the different forces acting on a body.  quantitatively, force is a vector quantity defined as the rate of change of momentum induced by the force, and therefore has a direction associated. the si unit for force is the newton.  examples...  - a person holding a dog by a rope experiences the force applied by the rope on his hand, and the cause for its pulling forward is the force transmitted by the rope. - while standing still gravity pulls downwards, but the floor pushes upwards, and the net force is zero.