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Homework Help: Basic mechanical question

  1. Apr 14, 2010 #1
    1. The problem statement, all variables and given/known data
    1000N crate pushed at constant speed 300N at angle 20* below horizontal. I need to find the frictional coefficient.


    2. Relevant equations



    3. The attempt at a solution
    I don't think I am even diagramming this right but here goes, Downward force is (1000N)(9.8m/s^2) Upward is (300N)(Sin20*), To the right is (300N)(cos20*) an I have no idea about to the left... I was sick in class and am pretty behind now trying to play catchup but none of the examples in the book are quite like this and I cant find very relevant help elsewhere online. Plz help=]
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 14, 2010 #2

    PhanthomJay

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    Homework Helper
    Gold Member

    Is there a sketch that goes along with this problem? You first have to be sure of the direction of the 300 N applied force that acts at 20 degrees below the horizontal. Is this force pushing down and to the right or up and to the right? I interpret it as acting downward and to the right, in which case it has a downward component, not an upward one. After you resolve this dilemma, you need to draw a free body diagram and show all forces acting on the crate, in both the x and y directions. There are several. Then you need to apply newton's laws in the x and y directions. You will probably need to 'catch up' with what you missed in class by talking directly to your instructor, assuming your instructor is human and not a machine.
     
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