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Homework Help: Pulley problem

  1. Aug 10, 2007 #1
    1. The problem statement, all variables and given/known data
    A block with mass 6.00kg resting on a horizontal surface is connected by a horizontal cord passing over a light frictionless pulley to a hanging block with mass 4.00kg. The coefficient of kinetic friction between the block and the horizontal surface is 0.50. After the blocks are released,
    a.) Find the acceleration of each block
    b.) The tension in the cord.

    2. Relevant equations

    3. The attempt at a solution
    uk = 0.50
    fk = ukN
    fk = 0.50(6.00kg)(9.8m/s^2)
    Summation of the mass of 6.00kg block
    m1a = T - fk
    m1a = T - 0.50(6.00kg)(9.8m/s^2)

    Summation of the mass of 4kg block
    m2a = m2g - T

    so i add both the two forces:
    m1a = T - 0.50(6.00kg)(9.8m/s^2)
    +m2a = m2g - T
    (m1+m2)a = m2g - 0.50(6.00kg)(9.8m/s^2)
    a = { (4.00kg)(9.8m/s^2) - 0.50(6.00kg)(9.8m/s^2) } / {6.00kg+4.00kg}
    a = 0.98m/s^2

    dont know how the back of the book got an answer of 0.1m/s^2

    b.) m2a = m2g - T
    (4.00kg)(.98m/s^2) = (4.00kg)(9.8) - T
    T = 35.28N
  2. jcsd
  3. Aug 10, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Your method and answers look correct to me. (Must be a typo in the book.)
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