Understanding μk

  1. I'm currently a first year physics student and missed some nets and concepts and need help before exams. It would be a HUGE help if someone could explain it to me and how to use it to find things like Fn and a→ when mass and μk is given. Please i really could use this info and thanks.
     
  2. jcsd
  3. Simon Bridge

    Simon Bridge 15,015
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    Welcome to PF;
    By ##\mu_k## do you mean the coefficient of kinetic friction?
    It's used the same way as any coefficient of friction.

    You use friction as an additional force in the free-body diagram.
    People tend to trip up on the direction (it changes if the velocity changes direction) and on the transition between kinetic and static cases.

    See:
    http://hyperphysics.phy-astr.gsu.edu/hbase/frict.html

    Hyperphysics appears to repeat an "obsolete idea" about friction re surface roughness.
    See: http://amasci.com/miscon/miscon4.html#fric
    ... does not affect the calculation though.
     
    Last edited: Jan 13, 2014
  4. yeah i was talking about it as as a coefficient of friction kinetic friction and thanks for the help!
     
  5. berkeman

    Staff: Mentor

    I'm impressed you were able to decode that, Simon! I didn't have a clue what the OP was asking... :smile:
     
  6. Simon Bridge

    Simon Bridge 15,015
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    @T_razz: no worries, do some examples and let me know if you get stuck.

    @berkeman: experience :D
    I need to edit my original reply slightly though: the coefficient is not the force. I'm sure nobody got confused...
     
  7. sophiecentaur

    sophiecentaur 13,698
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    Psychic?
     
  8. Simon Bridge

    Simon Bridge 15,015
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    I dunno - lets see... ummmm... I'm picking up an impression of a square or rectangle of light in front of you... also a general blockyness like an ordered cubism regularly under your hands.
    There's another in the background - it's fuzzy - associated with the letter D or C.
    Does this make any sense to you?
     
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