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Suspended steel beam 
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#1
Nov1804, 03:34 PM

P: 16

I'm having problems with what equation to use for this question:
A 1000 kg steel beam is supported by two ropes. Each rope has a maximum sustained tension of 6000N. Does either rope break? 


#2
Nov1804, 03:55 PM

Sci Advisor
HW Helper
P: 2,002

Draw a free body diagram.
The two tensions are directed along the ropes. The sum of the tensions is directed upwards and has magnitude F=mg (m=mass of the beam). 


#3
Nov1804, 04:01 PM

P: 527

Well, the weight causes a force of roughly 10*1000 = 10000 [N] on both ropes combined. But because of different angles, the forces caused by the ropes will not be the same. Let F_{1} be the force of the left rope (20 degree angle), and F_{2} the other force.
You know that the forces will have to keep the weight up, so the vertical components together must add up to 10000 [N] : F_{1} sin[20] + F_{2} sin[30] = 10000 Now the horizontal components will be directed in opposite direction, and will, because of that, have to be of equal size. So: F_{1} cos[20]  F_{2} cos[30] = 0 You can solve F_{1} and F_{2} from these equations, and check if any of the ropes will break. 


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