When a soccer ball is kicked the resulting motion of the ball is determined by Newton's laws of motion. From Newton's first law, we know that the moving ball will stay in motion in a straight line unless acted on by external forces. A force may be thought of as a push or pull in a specific direction; a force is a vector quantity. If the initial velocity and direction are known, and we can determine the magnitude and direction of all the forces on the ball, then we can predict the flight path using Newton's laws.