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Homework Help: Newton's forces on a box

  1. Feb 21, 2010 #1
    Newton's forces on a box!!!!!!!!

    1. The problem statement, all variables and given/known data
    Two 45 N forces and a 90 N force act on a hanging box as shown in the picture below.

    Will the box experience acceleration?
    1. Yes; upward.
    2. No; it is balanced.
    3. Unable to determine without the angle.
    4. Yes; downward.

    2. Relevant equations
    F= ma


    3. The attempt at a solution
    Will the two forces at the top result in a +y direction force of 45 or 90, or is it something else.
     

    Attached Files:

  2. jcsd
  3. Feb 21, 2010 #2
    Re: Newton's forces on a box!!!!!!!!

    You know that the Y-component of each of the 45 N forces is less than 45 N (since 45 N is the hypotenuse of the triangle that the components make) Therefore, both of them summed is less than 90 upward. If you have 90 downward and less than 90 upward, do you have an acceleration? Note also that the x-component of one 45 N force cancels out the other's due to symmetry.
     
  4. Feb 21, 2010 #3
    Re: Newton's forces on a box!!!!!!!!

    thanks i get it!
     
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