Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    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?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook