Newton's third law of motion

Change in the position of an object

For other uses, see Motion (disambiguation).

In physics, motion is when an object changes its position with respect to a reference point in a given time.

Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed, and frame of reference to an observer, measuring the change in position of the body relative to that frame with a change in time.

The branch of physics describing the motion of objects without reference to their cause is called kinematics, while the branch studying forces and their effect on motion is called dynamics.

If an object is not in motion relative to a given frame of reference, it is said to be at rest, motionless, immobile, stationary, or to have a constant or time-invariant position with reference to its surroundings.

Modern physics holds that, as there is no absolute frame of reference, Isaac Newton's concept of absolute motion cannot be determined.^[1] Everything in the universe can be considered to be in motion.^{[2]: 20–21&#}

an object is not in motion when

an object is said to be in motion when