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What is the acceleration of a crate after it has just started to move?

  1. Feb 5, 2010 #1
    1. The problem statement, all variables and given/known data

    The coefficients of static and kinetic friction between a 445 N crate and the warehouse floor are 0.565 and 0.450, respectively. A worker gradually increases his horizontal push against this crate until it just begins to move and from then on maintains that same maximum push.

    2. Relevant equations
    What is the acceleration of a crate after it has just started to move?

    3. The attempt at a solution

    I tried to multiply the kinectic friction coefficient by the Normal Force to get kinetic friction. Then I tried to divide Kinectic Friction by the mass of the box and I got:

    4.39 m/s2 but it was wrong.
  2. jcsd
  3. Feb 5, 2010 #2
    The force needed to start moving the box is F_static= mu_static * Normal
    Once the box starts moving the force of kinetic friction is F_kinetic=mu_kinetic *normal

    The net force at that point is F_net=F_static-F-kinetic
    a = F_net/mass_crate
  4. Feb 5, 2010 #3
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