Meterstick against wall

  • Thread starter proace360
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  • #1
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Homework Statement


A 0.13 kg meter stick is held perpendicular to a wall by a 2.7 m string going from the wall to the far end of the stick.
(a) Find the tension in the string.
(b) If a shorter string is used, will its tension be greater than, less than, or the same as that found in part (a)?
(c) Find the tension in a 2.0 m string.


Homework Equations



Torque=Nr?

The Attempt at a Solution


I discovered the angle to be 68.38 degrees, and I thought that, since the y-component of the force cancels out mg, T=mg/sin(theta). Why is it wrong?
 

Answers and Replies

  • #2
Doc Al
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The string tension is not the only force (besides the weight) acting on the stick.
 
  • #3
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I know that the wall exerts a horizontal force, but that doesn't matter in the Fy equation.
 
  • #4
Doc Al
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But the vertical force it exerts does.
 
  • #5
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wait... how does it exert a vertical force? Is there a friction force?
 
  • #6
Doc Al
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wait... how does it exert a vertical force? Is there a friction force?
There better be. But you need not worry about the wall force to solve this problem.
 

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