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How to find Coefficient of Friction w/ Fa and mass?

  1. Mar 23, 2015 #1
    1. The problem statement, all variables and given/known data
    A team of six poodles are pulling a 14.0 kg sled at 8.0 m/s

    IF the dogs are applying a 66N force, find the coefficient of kinetic friction

    2. Relevant equations
    Ff=u*Fn
    Fnet=ma
    Fnet=(-Ff)+Fa


    3. The attempt at a solution
    I honestly have no clue where to start for this question.
     
  2. jcsd
  3. Mar 23, 2015 #2

    PhanthomJay

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    Well you have correctly listed the relevant equations, now first identify what the acceleration is and solve. Read the problem carefully.
     
  4. Mar 23, 2015 #3
    So I started by finding the Net Force which was 0 due to the fact that there is no acceleration (velocity is constant).
    Then found Force of Friction using Fnet and Fa with the formula Fnet=Fa+(-Ff).
    Then found Fn using Fn=mg.
    Finally, I user Ff=Fn*u to find u

    MY WORK
    1.
    Fnet=0 Fnet-Fa=-Ff 0-66=-Ff -66=-Ff
    2.
    Fn=mg Fn=14kg*9.8 Fn=137.2
    3.
    Ff=u*Fn u=Ff/Fn 66/137.2=u 0.48=u
     
  5. Mar 23, 2015 #4
    Please tell me if you see any errors in my calculations
     
  6. Mar 23, 2015 #5
    Does this look right?
    1.
    Fnet=0 Fnet-Fa=-Ff 0-66=-Ff -66=-Ff
    2.
    Fn=mg Fn=14kg*9.8 Fn=137.2
    3.
    Ff=u*Fn u=Ff/Fn 66/137.2=u 0.48=u
     
  7. Mar 23, 2015 #6

    PhanthomJay

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    Look
    Looks good!
     
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