Wind in a sail, and two equal bodies on an inclined plane
Why wind drives the sail more than the water; percussion of equal weights 10 and 10
Two mechanical questions share the leaf. A sailing boat, drawn at the foot of the page, prompts the argument that if the water moved as fast as the air the ship would run like the wind without a sail; but because the wind is faster higher up than lower down, the wind has more power in the sail than in the water. Above, a sphere and a rectangular block, each marked 10, rest on an inclined plane, and Leonardo asks what difference there is in the percussion of two bodies of equal weight struck upon an equal slope.
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Percussion of a sphere and a block on equal obliquity
A sphere and a parallelepiped, each marked 10, are set on the same inclined plane. Leonardo asks what difference there is in the percussion of these two bodies, given that they are of equal weight and struck upon an equal slope.
Wind faster aloft gives the sail more power than the water
If the water moved as fast as the air, the ship would move like the wind without a sail. But because the wind is faster higher up than lower down, the wind therefore has more power acting in the sail than in the water.