In physics, motion is the change in position of an object or fluid with respect to a reference frame over a given time. Motion is mathematically described in terms of vector quantities such as displacement (with direction and distance), velocity (direction and speed), acceleration, etc. The relative motion of an object with respect to an observer is the object's motion described in the observer's comoving frame, quantified in terms of relative position, relative velocity, etc. The branch of phys...
