what is the law where an object in motion remains in motion and an object at rest remains at rest unless an outside force acts on it?

What is a hitters law if he is hitting a ball with a bat ?

What is the acceleration of an object that's produced by a net force directly to a magnitude as the net force, same direction, and proportional to the mass of the object?

What is the law when there is an action but there is an opposite or equal reaction?