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Coefficient of static friction

  1. Sep 27, 2009 #1
    1. The problem statement, all variables and given/known data

    A block of mass m is resting on a horizontal surface whose coefficient of static friction is μs.

    http://bcs.whfreeman.com/WebPub/Physics/tiplerphysics6e_bridge/question_bank_images/fig5-65.png?2439

    Which of the following statements (if any) are true?

    A. If you want to apply the minimum possible force to move the block, you should apply it with the force pulling upward at an angle θmin = arctan μs.
    B. The minimum force necessary to start the block moving is μs mg/ √1 + μs2.
    C. Once the block starts moving, if you want to apply the least possible force to keep it moving, you should keep the angle at which you are pulling the same.

    There may be more than 1 answer

    2. Relevant equations

    Fs=μs Fn

    3. The attempt at a solution

    No idea.
     
  2. jcsd
  3. Sep 28, 2009 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi sonutulsiani! :smile:

    Call the normal force N, and the friction force H.

    Then do a vector triangle or x and y component equations for a fixed angle θ …

    what do you get? :smile:
     
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