Please note this is a very serious thread. Please note Newton's First Law: First law: When viewed in an inertial reference frame, an object either remains at rest or moves at a constant velocity, unless acted upon by an external force. Here is an experiment to prove this First Law wrong. Consider two balls rolling at a constant velocity directly toward each other on a frictionless plane. Ball A is heading due east at 5 m/s and Ball B is heading due west at 5 m/s. The balls engage in an inelastic collision. The balls will both come to rest. This can be proven experimentally. Please note that Newton's Second Law describes Force = Mass * Acceleration. Neither ball has an acceleration, meaning that neither ball has any force associated with it. So despite not being acted upon by any FORCE, during the collision, the balls change velocity from 5 meters/second to zero. This simple experiment clearly shows that an object will not necessarily stay in motion at a constant velocity despite not being acted upon by an external force.