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Homework Help: Conceptual Friction Question

  1. Sep 25, 2011 #1
    1. The problem statement, all variables and given/known data
    A 3-lb horizontal force is applied to a 10-lb block on a rough horizontal surface. The block is initially at rest. If [itex]\mu[/itex]s is 0.5 and the [itex]\mu[/itex]k is 0.4, the frictional force on the block is?


    2. Relevant equations
    FN=mg
    Fk=[itex]\mu[/itex]kFN
    Fs,max=[itex]\mu[/itex]sFN


    3. The attempt at a solution
    I found [itex]\mu[/itex]s,max required to move the 10-lb block was 49.0 lb/ms^2..or approximately 22N.

    Since the force being applied is 3-lb, or approximately 1.4N, then the frictional force must be equal to the force being applied correct?

    Thanks.
     
  2. jcsd
  3. Sep 26, 2011 #2

    PeterO

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    Homework Helper

    Sounds good - especially in America where apparently the pound is a unit of Force, not a unit of mass.
     
  4. Sep 26, 2011 #3
    Thank you!
    Yeah only here in America haha..
     
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