What does the term friction mean

  1. 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.


  2. jcsd
  3. russ_watters

    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.
  4. Am I using the term "lateral" correctly if I use it to mean non perpendicular?
  5. 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.
  6. for direction, always use this 'friction is always in the direction which opposes sliding' It helped me get through some tough Mechanics finals.


  7. SGT

    SGT 0

    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.
  8. The key point of the post was 'thought of'
  9. 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.
  10. cepheid

    cepheid 5,189
    Staff Emeritus
    Science Advisor
    Gold Member

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