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Homework Help: Box Promblem

  1. Dec 8, 2005 #1
    I really don't undersand the friction chapter in my physics book, can somebody please help with one question. "Two crates of a mas of 75 and 110 kg are at rest on a horizontal surface. A 730 N force is exerted on the 75 kg box. If the coeff. of kinetic friction is .15 what is the acceleration of the boxes and the force each box exerts on the other?
    Can somebody at least tell me what formaula to use. Im completely lost :frown:
  2. jcsd
  3. Dec 8, 2005 #2


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    Homework Helper
    Gold Member

    1) Draw the Free body force diagram for each box.

    2) Write down the relations between the forces and acceleration for each box in the horizontal and vertical directions.

    3) From the equations you can find the net acceleration and force each box exerts on the other.

    Show us where exactly in the problem you are stuck. It will be easier to help that way.
  4. Dec 8, 2005 #3


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    Force = mass*acceleration (isn't this some law)

    you have... Force - Ffriction = mass*acceleration

    you know F
    you know your masses
    what is friction? your freebody will tell
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