Pulley and cord: how the cord's angle changes the force
A suspended rod and three pulley figures showing equal weights that resist unequally
A suspended-rod balance diagram at the top is followed by three figures of weights joined by a cord running over a pulley. Leonardo states that when the two parts of the cord leaving the pulley are equally placed, the equal powers at their ends resist equally, as at f. But when the two parts sit at unequal positions, equal weights come to appear unequal, and the more unlike those positions, the more varied the powers that resist one another.
On this page
Equal powers over a pulley resist equally when symmetric
When the two parts of the cord coming out of the pulley are equally placed, the equal powers joined to their two ends resist one another equally, as at the point f. This is the balanced case against which the others are measured.
Unequal cord positions make equal weights seem unequal
The inequality of the positions taken by the two parts of the cord leaving the pulley makes equal powers attached to the ends appear unequal. The more unlike the positions, the more varied the powers that resist each other.
Suspended-rod diagram
The topmost figure is a horizontal rod hung by cords with a weight below, its numeric labels tallying the balance. It continues the running study of the equilibrium of weights.