Newton's First Law   

Isaac Newton's first law says that "An object in motion tends to stay in motion while an object at rest will stay at rest, unless acted upon by an outside force."  Simply, this means that nothing can move on its own.  A pool ball will not just start rolling for fun.  A force must act upon it so it can move.  When the cue ball is hit, it will keep moving unless it collides with a ball or the outside edges of the pool table.  When the kinetic energy is fully transferred to another ball the cue ball will stop moving.  That process is described in our Collisions page.

          Newton's Second Law

Newton's second law states that force is proportional to mass times the acceleration.  This law means that the bigger the object, the more force is needed to accelerate that object. Also,  the heavier an object, more force is required to move it.  If billiards balls had a mass of 5 kg. and a the player wanted the ball to move at 2 meters per second squared, then he or she would need 10 Newtons of Force to achieve that goal.

         Newton's Third Law

Newton's Third Law states that for every action, there is an equal and opposite reaction.  Translated, this means that for every force, there is an equal or opposite force.  When one strikes a ball, that ball exerts an equal force on the stick.  Another example of this principle is if you were holding up a Physics book.  There are two forces acting on that book.  The force of your hand holding up the book and the force of gravity pulling down on the book.