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AP Physics~Work

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  1. Oct 9, 2012 #1
    A crate is dragged 15m along a horizontal surface by a rope which makes an angle of 37° with the horizontal. How much work is done?
     
  2. jcsd
  3. Oct 9, 2012 #2

    lewando

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    How much work do you think is done?
     
    Last edited: Oct 9, 2012
  4. Oct 9, 2012 #3
    Is there gravity, if so Earths? Are we neglecting vertical work?
     
  5. Oct 9, 2012 #4
    I THINK we are ignoring the vertical
     
  6. Oct 9, 2012 #5
    @lewando i am not sure where to start with this problem
     
  7. Oct 9, 2012 #6

    lewando

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    Assuming you know W = F*d, you have d, you need F. By "dragged" assume no acceleration. What force would resist your dragging force?
     
  8. Oct 9, 2012 #7
    Okay, just assume there's gravity strong enough that no matter how much work we put into vertical work, it will not move.
    Work in this case, is split into two components, vertical and horizontal. Since we are ignoring the vertical component (because we'll assume something like the normal force by the ground + Force applied by you upwards = gravitational force).
    So we only have to find the horizontal component.
    But we don't even know the force applied yet.
     
  9. Oct 9, 2012 #8

    lewando

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    @Cbray: also m, also μ.
     
  10. Oct 9, 2012 #9
    Is this problem unsolvable?
     
  11. Oct 9, 2012 #10
    We can't solve the amount of energy given to the crate without an external force, so information wise, yes it seems unsolvable unless you were given extra information.
     
  12. Oct 9, 2012 #11

    lewando

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    The frictional reaction force is unknowable. So good call.
     
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