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Homework Help: Compute the resulting acceleration

  1. Feb 23, 2010 #1
    1. The problem statement, all variables and given/known data

    A 100 kg trunk loaded with old books is to be slid across a floor by a woman who exerts a force of 500 N down and forward at 30° with the horizontal. If μk = 0.3 and μs = 0.4, compute the resulting acceleration.


    2. Relevant equations and 3. The attempt at a solution

    N = mg, of trunk
    N = 100kg * 9.8 = 980 N
    Push of lady :
    N = F sin theta
    N = 500N * sin 30 = 250N
    Total force being exerted = 980 + 250N = 1230N
    friction kinetic force:
    f = u*N
    f = .3 * 1230N
    friction force of moving box = 369N

    woman pushes with force:
    500N * cos 30 = 433N
    So with 433N force of push - 369N friction = 64N of net force on sliding box
    Net force = mass * acceleration
    64N = 100kg * a
    acceleration = 0.64 m/s^2 => INCORRECT => Please help!
     
  2. jcsd
  3. Feb 24, 2010 #2
    we know the formula F=macos theta. and F=mue*mg.from this u can find the force and equal both and find out accelaration
     
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