What is the largest value of Fw the cords can withstand?

  • #1

Homework Statement



Cords can withstand a maximum tension of 80N. What is the largest value of Fw they can support?

Homework Equations



Ft1 and Ft2 are 80.

FsysX = Ft1 sin 60 + Ft2 sin 70, but x doesn't matter

Fsys Y = Ft1 cos 60 + Ft2 cos 70 - Fw

The Attempt at a Solution



80 cos 60 + 80 cos 70 - Fw
Fw= 40+ 27
Fw = 67, when it should be 55.
 

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  • #2
SammyS
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Homework Statement



Cords can withstand a maximum tension of 80N. What is the largest value of Fw they can support?

Homework Equations



Ft1 and Ft2 are 80.

FsysX = Ft1 sin 60 + Ft2 sin 70, but x doesn't matter (It does matter.)

Fsys Y = Ft1 cos 60 + Ft2 cos 70 - Fw

The Attempt at a Solution



80 cos 60 + 80 cos 70 - Fw
Fw= 40+ 27
Fw = 67, when it should be 55.
It's a mistake for you to assume that both F1 and F2 are equal to 80 N. That will lead to a non-equilibrium condition in the x-direction.

Probably only one of them will be at the maximum value. You should be able to solve for Fw in terms of F1 or F2 .
 
  • #3
It's a mistake for you to assume that both F1 and F2 are equal to 80 N. That will lead to a non-equilibrium condition in the x-direction.

Probably only one of them will be at the maximum value. You should be able to solve for Fw in terms of F1 or F2 .

So I should say, for example, T1 is going to be equal to 80, solve for T2 in the X direction using that, then use those to solve for the weight.

I'll try it! Thank you!
 
  • #4
SammyS
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Yes, you can try that. It may turn out that doing this gives you that T2 > 80 N, in which case you will need to assume that T2 = 80N.
 

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