Understanding μk for Physics Students: Exam Prep Help

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Discussion Overview

The discussion revolves around understanding the coefficient of kinetic friction (μk) and its application in physics problems, particularly in the context of exam preparation for first-year physics students. Participants explore how to use μk to find normal force (Fn) and acceleration (a→) when mass and μk are provided.

Discussion Character

  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant seeks clarification on how to apply μk in calculations involving normal force and acceleration.
  • Another participant confirms that μk refers to the coefficient of kinetic friction and explains its role in free-body diagrams, noting common pitfalls related to direction and the transition between kinetic and static friction.
  • A participant expresses surprise at the initial confusion regarding the original question, indicating a lack of clarity in the phrasing.
  • There is a suggestion to practice examples and reach out for further help if needed, indicating a supportive approach to learning.
  • One participant humorously comments on the ability to interpret the original post, while another makes a light-hearted remark about psychic abilities, which diverges from the technical discussion.

Areas of Agreement / Disagreement

Participants generally agree on the definition and application of μk, but there is some confusion regarding the original question and its clarity. The discussion does not reach a consensus on specific examples or methods, as it remains exploratory.

Contextual Notes

Some assumptions about the understanding of friction and its application in physics problems may be missing, and the discussion does not resolve the clarity of the original question posed by the first participant.

T_razz
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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.
 
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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:
yeah i was talking about it as as a coefficient of friction kinetic friction and thanks for the help!
 
I'm impressed you were able to decode that, Simon! I didn't have a clue what the OP was asking... :smile:
 
@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...
 
Psychic?
 
I don't know - let's 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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