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A Torque question

  • Thread starter kitty9035
  • Start date
17
0
1. Homework Statement
A window washer is standing on a scaffold supported by a vertical rope at each end. The scaffold weighs 185 N and is 3.47 m long. What is the tension in the rope nearest the 747 N window washer when he stands 1 m from one end?


2. Homework Equations

sum of torques = zero
acceleration of gravity equals 9.8 m/s2

3. The Attempt at a Solution

I thought it was a simple problem but I get the answer wrong. My answer is 681.27 N. Is that right? If not how do i get the right answer??:eek:
 
32
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The first thing you need to do is to find an appropriate axis and put down all the torque effecting that point both clockwise and counterclockwise. Remember that the scaffold exerts its from the center of its mass.
 
17
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I thought I did that. Is this the right set up?
0+185N(sin-90)(-1.735m) + 747N(sin-90)(-2.735)-3.47T=0
 

Hootenanny

Staff Emeritus
Science Advisor
Gold Member
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I thought I did that. Is this the right set up?
0+185N(sin-90)(-1.735m) + 747N(sin-90)(-2.735)-3.47T=0
Here is your problem. Rewriting what you have written we have;

[tex] {\color{red}-}(185\times1.735){\color{red}-}(747\times2.735){\color{red}-}(3.47\times T)=0[/tex]

This would mean that all the torques would tend to rotate the scaffold in the same direction, is the really what is happening?
 

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