Free solo. Humans are in motion in a variety of ways. If gravity is the only influence acting, then the acceleration is always downward.

Car crash. An object will travel in one direction forever or until an outer force changes its direction.

Runner. When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

Laws of motion.​​​​​​​ The motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame with change in time.

Open sea. The acquisition of knowledge in physics proceeds in close interlocking of experiment and theory.

Return. The smaller scales of these motions are too small to be detected conventionally with human senses.