Apparent speed of runners; weight over a wedge
Relative motion doubling the seen speed, with wedge-and-weight and pulley studies
Folio 64v opens 'On motion' with an observation on relative velocity: if two files of runners pass in opposite directions along one line, and the second file lies between the eye and the first, each will appear to move at double its true speed. The runners are labelled a b (running toward d) and c d (toward a), with the eye at f. The rest of the sheet is mechanics: pulley-and-weight arrangements (the '4 4 4 4' figures) at upper left, and two inclined-plane rollers labelled 'weight drawn over the wedge' and 'wedge drawn under the weight.'
On this page
Opposed runners appear twice as fast
If many run one after another along one line, and others run the opposite way, and the second file lies between the eye and the line of the first runners, the motion of each appears double the swifter than its true course. The first runners a b go toward d, the second c d toward a, and f is the eye that sees them.
Weight and wedge on the inclined plane
Two rollers on inclined planes are labelled: one a 'weight drawn over the wedge,' the other a 'wedge which is drawn under the weight,' showing the wedge and its load resolved along the slope.
Weights hung on cords
Pulley-and-weight arrangements at the upper left, marked '4 4 4 4', hang graduated weights from cords to compare the forces acting along them.