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Homework Help: Incline Problem

  1. Oct 11, 2009 #1
    Problem: Block 1 is 7kg and is resting on a table with friction. Block 2.5kg is connected by a massless cord and is hanging over the side of the table. ( assume there is no friction on the cord where it goes over the side of the table.) The two masses are stationary but on the verge of sliding.
    a.) Draw a free body diagram
    b.) What is the magnitude of the frictional force holding the blocks in place? (static friction.)
    c.) What is the coefficient of static friction between the table and the block?
    d.) If you give the blocks a slight nudge, they begin to move. If the coefficient of kinetic friction is 0.54, what is the frictional force (kinetic) now that they are moving?

    I draw the free body diagram and understand their is Fg, Fnormal, Ffriction, Ftension on block 1, then block 2 has Ftension and Fg. Not really sure what to do next to solve for frictional force. By the way whats the difference between static and kinetic friction? My book eludes this information to me.
  2. jcsd
  3. Oct 12, 2009 #2


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    There is obviously a force from the block hanging over the table trying to pull the one on the table off. If they're on the brink of moving then the frictional force must be equal to the force trying to move them. Here is a link that has a couple of articles on the differences between the frictions.

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