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Homework Help: Can someone check this?

  1. Feb 7, 2004 #1
    a 70 kg box s pulled by a 400 N force at an angle of 30 degrees to the horizontal. The force of kinetic friction is 75 N.

    determine the acceleration.

    heres what i did

    first i found the x-component using (686)sin30 and it comes out to be 343.

    Then i use the formula where the sum of forces = m*a and i plug in the numbers. 343=70a. divide by a and accelertaion is 4.9 m/s/s. is that right?
  2. jcsd
  3. Feb 7, 2004 #2


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    Science Advisor
    Gold Member

    The horizontal component of the tension should be 400*cos(30)~346 N

    The sum of forces in the x direction is then 346 - 75 = ma

    solve for a ~ 3.9 m/s/s.
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