2007-12-11 01:36:01 · 5 answers · asked by Dustin P 1 in Science & Mathematics ➔ Physics
No surface is perfectly smooth and even if it were, many molecules of the two surfaces would get close enough together to interact.
2007-12-11 01:49:35 · answer #1 · answered by Tim C 7 · 0⤊ 0⤋
If you reduce the bumps by a factor of 10 with sandpaper, you get 100 times as many on the surface. You can only see roughness down to about a micron. Atoms are a thousand times smaller than that. Friction is ultimately due to atoms pushing on atoms, and atoms are lumpy.
2007-12-11 02:06:48 · answer #2 · answered by Dr. R 7 · 0⤊ 0⤋
The closer you look, the rougher the surface is. On an atomic scale, most surfaces look like mountain ranges, with peaks and valleys. The degree of peaks and valleys is part of the issue. Another issue is the types of atoms that are on those peaks. If the two surfaces are metal and if you suppose that those metal surfaces are perfectly clean (the atoms on the surface are metal atoms rather than oxygen, chlorine, sulfur, etc), the atoms would bond to the atoms on the other surface and the two pieces would become one piece. In practice, there are no perfectly clean surfaces on an atomic level.
2007-12-11 01:49:12 · answer #3 · answered by Gary H 7 · 0⤊ 0⤋
Partly because smooth objects at a microscopic range are actually bumpy.
2007-12-11 01:47:45 · answer #4 · answered by Brian 6 · 0⤊ 0⤋
particles do have frictional force. so any contact of 2 ojects must have friction//
2007-12-11 01:58:48 · answer #5 · answered by Anonymous · 0⤊ 0⤋