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Homework Help: Acceleration of gravity problem

  1. Mar 5, 2010 #1
    1. The problem statement, all variables and given/known data
    A(n) 43 kg block is pushed along the ceiling
    with a constant applied force of 560 N that
    acts at an angle of 67◦ with the horizontal,
    as in the figure. The block accelerates to the
    right at 4.5 m/s2.
    The acceleration of gravity is 9.8 m/s2 .
    What is the magnitude of the normal force
    the ceiling exerts on the block?
    Answer in units of N.

    2. Relevant equations
    Fn = mg

    3. The attempt at a solution
    I tried to find Fn = mg = 560sin67, it didn't work
    any ideas?
    Last edited: Mar 5, 2010
  2. jcsd
  3. Mar 5, 2010 #2
    Re: Forces!

    here's the image

    Attached Files:

  4. Mar 6, 2010 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Forces!

    The normal force, F_n, is the perpendicular contact force exerted by the ceiling on the block. It is not the weight of the block.
    Your equation makes no sense. 560sin67 is the upward vertical component of the applied 560 N force. Look at all the forces acting in the vertical direction, determine the net force acting in that direction, and then use one of Newton's laws to solve for F_n.
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