Rules of Percussion and the Rebound of Moving Bodies
Seven propositions on bounce angles, curved flight, and the conservation of impressed motion
A narrow strip carries seven terse propositions on the mechanics of percussion and rebound. Leonardo states that a struck body finds its place between equal angles, that swift rotation after a sharp bounce makes bodies of any shape appear spherical, and that a body's surface travels farther than its centre after bouncing. Further rules hold that a body driven in circular motion escapes on a curved path, that the quantity of begun motion is not lost but spent in successive bounces, and that the swiftest body is the one whose centre of gravity lies farthest from the perpendicular of the centre.
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Bounce between equal angles and apparent roundness
The place a body reaches by the percussion of a dart or of a struck body is found between equal angles. After a sharp bounce, the swift rotation of a body of any shape makes it appear spherical and act as if perfectly round, while each part of its surface travels farther than its centre.
Curved flight and the conservation of impressed motion
A body driven by circular movement makes a curved flight. The quantity of motion once begun is not diminished by opposition but is spent in various bounces; and the less the motion of the percussion in the object falls short of the motion of its cause, the less the motion after the bounce falls short of the first.