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Need help with friction problem

  1. Oct 17, 2004 #1
    Hi! Is anyone willing to help me with this friction problem?

    A box having a mass of 1.5kg is accelerated across a table at 1.5m/s². The coefficient of friction on the box is 0.3. What is the force being applied to the box? :confused:
     
  2. jcsd
  3. Oct 17, 2004 #2

    Pyrrhus

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    Use Newton's 2nd Law

    [tex] \sum_{i=1}^{n} \vec{F}_{i} = m \vec{a} [/tex]

    and remember

    [tex] F_{f} = \mu N [/tex]
     
  4. Oct 17, 2004 #3
    What do I do with the friction formula?
     
  5. Oct 17, 2004 #4

    Pyrrhus

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    Do you know what's the Normal force?
     
  6. Oct 17, 2004 #5
    Apparently Normal force is equal to Gravitational force so 1.5kg x 9.8m/s² is 14.7N. That should be the Normal force right?
     
  7. Oct 17, 2004 #6

    Pyrrhus

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    Yes, so

    Do because there's only acceleration on the x-axis do the forces analysis there.

    [tex] F_{applied} - F_{f} = ma [/tex]
     
  8. Oct 17, 2004 #7
    Do I move everything to one side of the equation to make it equal to zero?
     
  9. Oct 17, 2004 #8

    Pyrrhus

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    Why would you do that?

    Isn't your unknown F applied?

    [tex] F_{applied} = ma + F_{f} [/tex]

    Mass is known, acceleration is known, [itex] \mu [/itex] is known, and the Normal force is known (so Friction force is known).
     
  10. Oct 17, 2004 #9
    Ooooooh! Gotcha! Right! Thanks a million!
     
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