# What does the term friction mean

1. Mar 22, 2005

### bugler777

Does the term "friction" mean (or imply) that there are lateral forces acting between two surfaces?

I'm not so much interested in measuring the forces of friction as I am in understanding the meaning of the term. I hope my question is clearly stated.

Thanks,

Charles

2. Mar 22, 2005

### Staff: Mentor

Yes, for friction to occur there must be lateral forces. This should not be confused with calculating friction, for which the actual lateral forces are often irrelevant.

3. Mar 22, 2005

### bugler777

Am I using the term "lateral" correctly if I use it to mean non perpendicular?

4. Mar 22, 2005

### whozum

Friction can be thought of as two surfaces rubbing together, imagine rubbing two surfaces together, where there are infinitesimally small grooves on each surface that are clinging onto each other and letting go.

Calculating friction in physics refers to the overall effect of these grooves as the sufraces roll, which you will find depends directly on the perpendicular force.

Conventional Friction is the force exertion required to release the grooves from each other allowing objects to slide over each other.

5. Mar 22, 2005

for direction, always use this 'friction is always in the direction which opposes sliding' It helped me get through some tough Mechanics finals.

Regards,

6. Mar 28, 2005

### SGT

Friction is mainly of electrostatic origin. The electronic shells of each body are attracted by the nuclei of the other body, slowing the relative motion.

7. Mar 28, 2005

### whozum

The key point of the post was 'thought of'

8. Mar 28, 2005

### pack_rat2

That may be true with very smooth objects, but more often, it's due to the interlocking of the hills/valleys on opposing surfaces, at the microscopic level.

9. Mar 28, 2005

### cepheid

Staff Emeritus
Yeah, but what are those hills and valleys made of, fundamentally? All contact forces are fundamentally electrostatic in nature, as far as I know.