Falling Bodies, the Strength of a Cord, and Friction
Heavy things fall toward the center of the elements; a shorter twisted cord resists more
A page of six propositions on motion, force, and friction, without diagrams. Leonardo argues that a falling body seeks not the true center of the world's mass but the center of the spheres of the lighter elements, and that a cord doubled and twisted resists more weight the shorter it is made. He observes that a thin flexible rod does not obey the hand at its far end, that dragged bodies of equal weight and material show no difference in motion however much their contact, that a wheel on a thinner pole moves more easily, and that anything cut off by a sharp blow flies away at equal angles from the cut.
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Heavy bodies fall toward the center of the lighter elements
Nothing that falls makes its course to the center of the true gravity or quantity of the world, but only to the center of the spheres of the lighter elements, whence every heavy thing equally distant is driven.
A doubled, twisted, shortened cord resists more
If a cord resists a hundred pounds, by doubling and twisting it it will resist as much more weight as it is made shorter than before.
Friction: a wheel turns more easily on a thinner pole
There is no difference in the motions of dragged bodies of equal weight and material, however much more contact one has, for what one gains in touching the other burdens with its contact. A wheel guided upon a thinner pole moves more easily.