Friction in a vacuum?

Discussion in 'Physics' started by tjohnson, Jan 29, 2015.

  1. Papabravo


    Feb 24, 2006
    Friction depends on the normal force and the surface properties of two materials. There is no dependence on ambient pressure or lack thereof. Did your degree come from the University of Kingman Reef?
  2. MrAl

    Distinguished Member

    Jun 17, 2014

    This has probably been mentioned before, but are you talking about the resistance due to air near the surface of the earth vs that in free space where there is no air?

    Air resistance is due to the density of air and something moving through it experiences the molecules in the air.

    Sliding friction on the other hand depends on the surface roughness which has much less to do with the air because the surface friction will usually be much more than the air resistance. If the sliding friction was low, then the air might have a significant effect, but we usually aim to separate the two functions so we can understand them independently of each other, then add the two when needed.

    Since a vacuum is less dense than air, there would be less friction. We then get into the question of is there such a thing as a perfect vacuum.
  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    Last edited: Apr 11, 2017
  4. Sitara


    May 2, 2014
    nsaspook likes this.
  5. wayneh


    Sep 9, 2010
    The quality of answers here greatly exceeds the quality of the question.

    That's harsh. I went back and re-read the original question and it's fine.

    My opinion is that drag due to motion through fields is not friction. To my mind, friction requires matter moving against matter. Perfect vacuum would have zero 'air' friction.
    Last edited: Apr 13, 2017
    GopherT likes this.