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Homework Help: Friction formula problem?

  1. Sep 30, 2004 #1
    I am having trouble getting this formula to work and I know it is easy! I am having a momentary lapse in math knowledge!
    M1=571.4g M2=550g a=.155m/s(sqr) find the force of friction using a=(M1-M2-Mf)g/(M1+M2) or is it M1g-M2g-f=(M1+M2)a
    I am having problem getting f by itself, any help?
    Last edited: Sep 30, 2004
  2. jcsd
  3. Sep 30, 2004 #2


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    ((M1+M2)a/g)-M1+M2=-Mf multiply the denominator on both sides, divide by g then use addition to isolate Mf
  4. Sep 30, 2004 #3


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    Homework Helper

    [tex] a = \frac{(M_{1}-M_{2}-F_{f})g}{M_{1}+M_{2}} [/tex]

    [tex] a(M_{1}+M_{2}) = M_{1}g-M_{2}g-F_{f}g [/tex]

    [tex] \frac{a(M_{1}+M_{2}) - M_{1}g + M_{2}g}{-g}= F_{f} [/tex]
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