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PLEASE help me solve this question about friction.

  1. Oct 27, 2009 #1
    Q1.A bartender slides a beer stein of mass 0.45kg horizontally along the bar with an initial speed of 3.5m/s. The stein comes to rest near the customer after sliding 2.8m. Find the coefficient of kinetic friction.

    Please help me >__>
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 27, 2009 #2


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    Please list your relevant equations and your attempt at a solution, and someone will be glad to help. You can use energy methods or the kinematic equations and Newton's laws.
  4. Oct 27, 2009 #3
    Thanks for replying but I have no idea how to solve it :(. I fail so much please help.
  5. Oct 27, 2009 #4


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    I can understand the difficulty you may be having with Physics, but it won't do you much good if we just crank out the method and solution for you. Besides, it is against PF policy to just hand out answers. Have you studied energy methods or at least studied the basic kinematic motion equations, and Newton's 2nd law? They are key to getting a grip on the physics of objects in rest or in motion.
  6. Oct 27, 2009 #5
    From what I know newton sceond law says when forces are unbalanced a object is accelerating. Also acceleration is directly proportional to force and inversely proportional to mass.Other than that I feel lost in that problem I dont know how to apply the law. :(
  7. Oct 27, 2009 #6
    Think about what do you know about the object. What is it doing? Why is it doing that?
  8. Oct 27, 2009 #7
    The best thing i could think of is this vf^2=v0^2+2ax

    vf=final velocity=0m/s
    v0=initial velocity=3.5m/s
    a=acceleration= solve for this

    To find a then multiply it by mass to find force.
  9. Oct 27, 2009 #8
    Sounds good to me.
  10. Oct 27, 2009 #9
    I am hopeless after that what do I do?
  11. Oct 27, 2009 #10
    Again, think about what you know about the object. What can you think of that applies to this other than Newton's second law?
  12. Oct 27, 2009 #11
    Nvm found it can you check if its right http://img263.imageshack.us/img263/7161/physics.png [Broken]
    Last edited by a moderator: May 4, 2017
  13. Oct 27, 2009 #12
    Again, looks good to me. Don't forget to match your significant digits.

    Quick question, what did you learn from this?
  14. Oct 27, 2009 #13
    To know how to apply the formula I guess.
  15. Oct 27, 2009 #14
    I guess it didn't come out well in text. I mostly meant that humorously.
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