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Blocks, Friction Forces and Acceleration

  1. Oct 15, 2005 #1
    I am having trouble with this problem:
    A block whose weight is 50.0N rests on a horizontal table. A horizontal force of 25.0 N is applied to the block. The coefficients of static and kidnetic friction are 0.510 and 0.350 respectively. Will the Block move under the influence of the force and if so, what will be the block's acceleration?
    What I have so far:
    1. Fs=mu sN
    =25.5 N
    25.5 N>25.0 N, therefore the block will move under the influence of the force.
    2. Finding acceleration
    I know I have to find the net force then use that in the second law equation. How do I do that.
    I have kinetic force=17.5, mass=50/9.8=5.10 kg.
    Please help!:cry:
  2. jcsd
  3. Oct 15, 2005 #2


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    You might want to look at this again. Which one was the force due to static friction?
  4. Oct 15, 2005 #3

    Chi Meson

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    You are correct so far.

    Think Newton's second law: the pulling force stays the same, but now instead of static friction, there is kinetic friction. What's the net force?
  5. Oct 15, 2005 #4
    Would the net force be: applied horizontal force-kinetic friction force?
  6. Oct 15, 2005 #5

    Chi Meson

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    yes, that's correct (there are two other forces in the vertical direction, but Normal force and weight will balance each other in *this* situation).
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