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Homework Help: Finding Accerleration on a slope with friction

  1. Oct 7, 2008 #1
    **Sorry the latex didn't really work for me.**
    1. The problem statement, all variables and given/known data
    In the figure below, m1 = 3.6 kg, m2 = 5.1 kg, and the coefficient of kinetic friction between the inclined plane and the 3.6-kg block is μk = 0.25. Find the magnitude of the acceleration of the masses.

    m1 = 3.6 kg
    m2 = 5.1 kg
    μ = 0.25
    Theta = 30

    2. Relevant equations
    a = ((m2*g)-(m1*g*sin(theta)))/(m1+m2)


    3. The attempt at a solution
    Since there is friction I did [tex] (m1*g*sin(theta)-μ*Fn
    Fn = (.5*m1*g*3^.5)

    a = ((5.1 kg*9.8 m/s^2) - (3.6 kg*9.8 m/s^2*sin(30)-.25(.5*3.6kg*9.8m/s^2*3^.5)))/(3.6kg+5.1kg)
    a = (50.031- (17.658 - 7.638))/(8.7)

    a = 4.599 m/s^2

    I got this wrong. please help
     
  2. jcsd
  3. Oct 8, 2008 #2

    alphysicist

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    Homework Helper

    Hi fallen186,

    There's not much detail about the problem, but the minus sign here means that m1 is moving down the incline. Is that what you intended?
     
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