r – m n -5 4

The lesser weight gives of itself, to the whole cord r n and r m, a weight equal to the 4 of n; but the weight m will not give to those cords more weight than 4 pounds. Therefore the cord n r feels neither more nor less weight than 8, that is n m, and the excess of m falls as gravity without support, and only the cord r m feels it — the moving body. The adversary says that what falls is not supported, and what is not supported gives no weight of itself to anything; but if it is moved by force, then that force is in the mover, slow or fast, because in it lies the excess.

Here the mover has power over it only by its excess, which is one. Therefore r moves with a velocity of one by violent motion, and not because 5, the mover, moves with a velocity of one — that is, the excess.

The thing that falls has no support; therefore it gives no weight of itself to anything, and for this reason its cord does not feel it. It is answered that if its cord did not feel it, it would not descend. Each of the two cords that hang from the opposite sides of the pulley feels all the weight joined to it; and this we prove by the balance, in which the weights placed on its right arm do not load the left arm in any part, and the division of those arms is the centre of the contact that the pole of the balance has with its support.

The adversary says that the thing which falls weighs only upon the air. It is answered that if it weighed no more than the air, it would not penetrate and would remain motionless. But every moving body penetrates the medium in which it moves by its excess; therefore the weight of the balance that descends descends only with that velocity with which its excess would descend, the excess being of such magnitude as its whole.

It is asked whether the very great excess increases weight in motion for its corresponding weight. Yes, by as much as the velocity is unsuited to it. The air above condenses it into so much greater density as the motion of the moving body is faster than the natural velocity of the air. But the cord always breaks at the boundary between natural and accidental motion, beside the contact condensed by the pulley, where lies the weight of the one and the other cord.

The cord of the moving body does not feel the weight of its mover.

The excess falls free, because it has no contact. Turn the page.

The excess is that which moves, and with so much more velocity as it is greater.

Never does the cord opposite to the excess feel more than the weight joined to it, except for the resistance of the air that condenses above it.