Environmental Engineering Reference
In-Depth Information
Fig. 3 Left hand side Leonardo's self-portrait. Right hand side sketches from da Vinci's notebook,
ca. 1480 demonstrating some of his notable friction experiments ( www.nano-world.org )
moved. Leonardo's experimental setup for macroscopic friction measurements was
rather simple. He measured the angle of an inclined plane, where a body, put on the
plane, started to slide and the weight needed to make a block on a table to move.
With this method, he was only able to measure static friction and most probably he
wasn't aware of the difference between static and kinetic friction. Leonardo found the
following two laws of friction, in which we essentially recover friction laws 1 and 2:
Law 1 . The friction made by the same weight will be of equal resistance at the
beginning of its movement although the contact may be of different breadths and
lengths.
Law 2 . Friction produces twice the amount of effort if the weight be doubled.
Amontons ( 1699 ), a French physicist (Fig. 4 ), two centuries after Leonardo's
discoveries, made experiments on a horizontal surface and measured the friction
Fig. 4 Left hand side Guillaume Amontons. Right hand side Amontons' experiment on multiplied
friction with overlapped horizontal plates (Amontons 1699 )
Search WWH ::




Custom Search