Newton's First Law Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. This we recognize as essentially Galileo's concept of inertia, and this is often termed simply the "Law of Inertia".

Newton's' Second Law The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors in this law the direction of the force vector is the same as the direction of the acceleration vector. This is the most powerful of Newton's three Laws, because it allows quantitative calculations of dynamics: how do velocities change when forces are applied. According to Newton, a force causes only a change in velocity (an acceleration); it does not maintain the velocity. This is sometimes summarized by saying that under Newton, F = ma. According to Newton an object with a certain velocity maintains that velocity unless a force acts on it to cause an acceleration (that is, a change in the velocity). Or in the case of a whip the mass decreases.

Newton's Third Law For every action there is an equal and opposite reaction. I think this is probably self explanatory.

Now if we add Galileo's findings on inertia (see below) We have a complete real world explanation of the action of a whip. Galileo's concept of inertia: an object in a state of motion possesses an " inertia'' that causes it to remain in that state of motion unless an external force acts on it. In order to arrive at this conclusion, which will form the cornerstone of Newton's laws of motion (indeed, it will became Newton's First Law of Motion), Galileo had to abstract from what he, and everyone else, saw. Most objects in a state of motion do NOT remain in that state of motion. For example, a block of wood pushed at constant speed across a table quickly comes to rest when we stop pushing. Galileo, by virtue of a series of experiments (many with objects sliding down inclined planes), realized that you must account properly for a hidden force: the frictional force between the surface and the object. Thus, as we push the block of wood across the table, there are two opposing forces that act: the force associated with the push, and a force that is associated with the friction and that acts in the opposite direction. (In the case of a whip this would be friction from the air and the inherent resistance of the material of the whip.) Galileo realized that as the frictional forces were decreased (for example, by placing oil on the table or in the case of a whip the mass is reduced) the object would move further and further before stopping. From this he abstracted a basic form of the law of inertia: if the frictional forces could be reduced to exactly zero (like reducing the mass and diameter of the the whip to almost zero) an object pushed at constant speed across a frictionless surface of infinite extent will continue at that speed forever after we stop pushing, unless a new force acts on it at a later time. Here the new force would be your hand holding the end of the whip or gravity.

Hope this helps in understanding the physics of the whip.