From Wikipedia: 1.First law: If an object experiences no net force, then its velocity is constant: the object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero) In other words, if something is moving, then it will continue moving until something affects that motion (friction, it runs into something, something runs into it, etc). Also, if something isn't moving, then it will continue to not move (remain at rest) until something causes it to move - something runs into it, something pushes it, etc. 2.Second law: The acceleration a of a body is parallel and directly proportional to the net force F acting on the body, is in the direction of the net force, and is inversely proportional to the mass m of the body, i.e., F = ma. In the first law, we indicated that something will maintain its velocity and direction until something affects that velocity or direction. The second law indicates that if the velocity is changing (either increasing or decreasing), then some force must be acting upon the object, and the amount of that force is proportional to the mass of the object times the acceleration (change in velocity over time) of the object. 3.Third law: When a first body exerts a force F1 on a second body, the second body simultaneously exerts a force F2 = -F1 on the first body. This means that F1 and F2 are equal in magnitude and opposite in direction. In other words, if you push on something, then it is going to push back with the same amount of force, but in the opposite direction. For example, the acceleration due to gravity causes us to "push" against the earth; and the earth pushes back.