On compound impetus and the three kinds of friction

On compound impetus.

Spiral traversed by truncated cones, with:

a simple motion g f - compound motion b - c d simple motion e

Analogous figure with a hemisphere:

Compound motion is that which participates in the impetus of the mover and in the impetus of the mobile, as is the motion f b c, which is in the middle between two simple motions, of which one is about the beginning of the motion and the other is about the end: a g is first, c d e c is at the end. But the first alone obeys the mover, and the last is only of the shape of the mobile.

On decompound impetus.

Decompound impetus accompanies the mobile with three natures of impetus, of which two arise from the mover and the third from the mobile. But the two of the mover are the straight motion of the mover mixed with the curved motion of the mobile, and the third is the simple motion of the mobile, which alone attends to turning the middle of its convexity to the contact of the plane, where it turns and rests.

Friction.

Dragged weight and pulley, with:

simple - a

The same with double friction and:

compound - c - b

Driven wedge, with:

decompound

Simple friction divides into 3 parts, that is simple and compound and decompound.

Simple friction is that which the mobile makes upon the place where it is dragged; compound is that which the mobile makes between two immobile bodies; decompound is that which the wedge makes on its different sides.

Spirale percorsa da tronchi di cono, con:

Figura analoga con semisfera:

Peso trascinato e carrucola, con:

Idem con doppio attrito e:

Cuneo conficcato, con:

Spiral traversed by truncated cones, with:

Analogous figure with a hemisphere:

Dragged weight and pulley, with:

The same with double friction and:

Driven wedge, with:

On compound impetus and the three kinds of friction

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Compound and decompound impetus

Simple, compound and decompound friction