|Leonardo da Vinci, Guillaume Amontons physics|
- Leonardo da Vinci started
- the study of rubbing surfaces,
- measuring the forces needed
- to pull different blocks across a surface,
- and finding that friction increases
- according to the weight of the object
- and not according to the size
- of its rubbing surface.
- Two centuries later, Guillaume Amontons
- added that friction doesn’t depend on speed.
- Da Vinci pulled blocks across
- a level table with no lubrication. Next,
- we pull blocks down an inclined table,
- and we test the effects of lubricating the table.
- We try different materials to find
- each combination has its own coefficient of friction.
- Rubber on clean dry concrete
- has thirty-three and a third times the friction
- of steel on ice, but rubber on wet concrete
- has only ten times the friction of steel on ice.
- If you put ice on that concrete
- then it’s even worse, so it’s good
- to do these experiments on table tops
- instead of in cars over icy bridges.
- Friction, wear, and corrosion, what happens
- from rubbing the cat the wrong way,
- rowing upstream, letting tires go flat,
- ignoring conflicts instead of resolving them,
- letting irritations accumulate into irreconcilables,
- and becoming irritable about unimportant things,
- makes a philosophy of life, remembering
- to check the air, lubricate the bearings,
- close the windows to conserve heat and reduce drag,
- smoothe out the wrinkles in the fabric,
- declutter, avoid meaningless minutia,
- and slip through obstacles like greased pigs.