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Movement of a plank

  1. Jul 10, 2013 #1

    adjacent

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    Here is a plank in empty space(There are no forces except one) .Someone is pushing it on a side.Will it rotate or Move straight in the direction of the force?
     

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  3. Jul 10, 2013 #2

    Doc Al

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    What do you think? Apply Newton's 2nd law for translation and for rotation.
     
  4. Jul 10, 2013 #3

    adjacent

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    I don't quite understand that.:confused:
     
  5. Jul 10, 2013 #4

    WannabeNewton

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    Write down ##F = ma## and ##\tau = I\alpha## for the system you drew.
     
  6. Jul 10, 2013 #5

    adjacent

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    OMG!What's ##\tau = I\alpha## ?
     
  7. Jul 10, 2013 #6

    Nugatory

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    Something that doesn't easily hit in google :)
    Try googling for "moment of inertia" and "torque"
     
  8. Jul 10, 2013 #7

    Doc Al

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  9. Jul 10, 2013 #8

    adjacent

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    I have not heard about anything about the moment of inertia or angular acceleration.Anyways,The plank will rotate,Am I right?
     
  10. Jul 10, 2013 #9

    Doc Al

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    The motion of the plank will be a combination of the translation of the center of mass plus rotation about the center of mass. It will rotate as well as translate.
     
  11. Jul 10, 2013 #10

    adjacent

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    Then where should I apply a force so the plank will only move straight without rotating?On the center of Mass?
     
  12. Jul 10, 2013 #11

    Doc Al

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    Yes, at the center of mass.
     
  13. Jul 11, 2013 #12

    adjacent

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    When I apply the force on the sides it will rotate and translate,What will happen if I remove the force.Will the plank keep rotating and translating or Move in a constant velocity in a straight line?
     
  14. Jul 11, 2013 #13

    Doc Al

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    When you remove the force, the center of mass will continue moving in a straight line at constant speed. And the plank will continue to rotate about its center of mass with a constant angular velocity.
     
  15. Jul 11, 2013 #14

    adjacent

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    Thank you So much Doc Al
     
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