The Nature of Force
Table of Contents
- We generally think that corporeal force is something easily understood.
Yet those who have examined it more carefully think otherwise. This is seen in the obscurity of the words they use to explain it.
Torricelli says that force and impulse are certain abstract, subtle things—quintessences—contained within corporeal substance like in Circe’s magic vessel.
Leibniz explains natural force as: “Active, primitive force, which is entelechia prima, corresponds to the soul or substantial form.”
They indulge in abstractions, using terms with no definite meaning—mere scholastic shadows.
- From that source arise various absurdities—such as the idea that the force of impact, however slight, is infinitely great.
This notion assumes that gravity is some real quality distinct from all others, and that gravitation is the operation of this quality, really distinct from motion.
Yet the slightest impact produces a greater effect than the greatest gravity without motion—for impact generates motion, while gravity alone does not.
Hence it follows that the force of impact exceeds the force of gravitation by an infinite ratio—that is, is infinitely great. See Galileo’s experiments and the writings of Torricelli, Borelli, and others on the defined force of impact.
- No force is immediately perceived by itself.
It is only known and measured by its effects.
But the dead force, or simple gravitation in a body at rest, produces no observable change and hence no effect.
But impact does.
Therefore, since forces are proportional to their effects, then dead force is null.
Yet it does not follow that the force of impact is infinite—just because it exceeds a null quantity by an infinite ratio does not mean it is infinite in itself.
- The force of gravity cannot be separated from momentum.
But momentum without velocity is nothing, since it is mass multiplied by velocity.
Velocity cannot be conceived without motion.
Thus, neither can gravitational force.
Moreover, force is known and measured only through action.
We cannot consider the action of a body apart from its motion.
Therefore, as long as a heavy body distorts the form of the lead beneath it or the cord suspending it, it is moving.
When it is at rest, it acts not at all, or in other words, is prevented from acting.
In short, the terms “dead force” and “gravitation” are assumed by metaphysical abstraction to signify something distinct from the mover.
But the moved, the motion, and the rest, are in reality nothing at all.
- If someone were to say that a hanging or resting weight acts upon the cord because it prevents the cord from springing back with its elastic force, I would reply that, by the same reasoning, any lower body acts upon an upper one resting on it because it prevents it from descending.
But we cannot say that the action of a body is to prevent another from occupying the space it already occupies.
- Sometimes we feel the pressure of a heavy body.
But this unpleasant sensation arises from the motion of the heavy object transmitted to our body’s nerves and fibers, changing their position;
Thus, it should be attributed to impact. In these matters, we suffer from many deep-rooted prejudices—but they must be overcome, or rather entirely driven out, by sharp and repeated reflection.
- In order to prove that any quantity is infinite, it must be shown that a finite, homogeneous part is contained in it infinitely many times.
But dead force is related to impact force not as a part to a whole, but as a point to a line, according to the very authors who assert the infinitude of impact force. Much more could be added here, but I fear becoming too long-winded.
- My principles solve the controversy over the proportion of forces.
One party thinks that momentum, motion, and impulse, for a given mass, are simply proportional to velocity. Yet they affirm that forces are proportional to the square of the velocity.
But this view assumes that a body’s force is distinct from its momentum, motion, and impulse.
Once that assumption is removed, the opinion falls.