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Sep16-07, 09:10 PM
P: 25
Tension in Cable

I thought that I had to assume the tension in the cables, otherwise how would I solve for the parameters given, ie: "range of values of Q which the tension will not exceed 270 in either cable."
Do you not solve by setting each tension to max (270 N) and then solving for Q... let's say I get Magnitude Q = xN then I would say 0<= Q <= xN?

So far I have done this

sum Fx: 340 cos 0 + 270 cos 90 + 270 cos 180 + Qx cos 240
I then solved for Qx cos 240 = -70

sum Fy: 340 sin 0 + 270 sin 90 + 270 sin 180 + Qy sin 240
I then solved for Qy sin 240 = -270

I then took the Qx component and Qy component and solved for Q using pythogras to yield 279.92 or 280 N at 60 degrees South of West.
So my final answer would be 0 N=< Q <= 280 N

I have no idea if this is correct, so any help with my methodology is welcome. Also if somone is able to confirm that they can't see the diagram I posted? I can view it without issue using several ISP's.