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Homework Help: Work-Energy with friction

  1. Sep 30, 2008 #1
    A rope and pulley have negligible mass, and the pulley is frictionless. The coefficient of kinetic friction between the first block (8 kg) and the table is [tex]\mu[/tex]=.250. The blocks are released from rest. USE THE ENERGY METHODS TO CALCULATE THE SPEED OF BLOCK 2 (6 kg) after it has descended 1.5 meters.

    Basically there's a diagram: Block #1 rests on the table and is connected by a rope that goes through a pulley to block #2, which is hanging off the table.

    E = K + U
    W = FDcos[tex]\Theta[/tex] = [tex]\Delta[/tex]E

    [tex]\Sigma[/tex]F = F(Tens) - F(fric)

    Block #1:
    E-initial = PE = (6)(9.8)(1.5)
    E-final = KE = 1/2 (6) v^2

    Block #2:
    E-initial = PE = ?
    E-final = KE = ?

    F = F(tens) - (8)(9.8)(.25)

    Whats the next step??
  2. jcsd
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