Statics Questions - Equilibrium in a pulley system

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Wilson123
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Homework Statement


Find the value of W to maintain equilibrium
upload_2015-12-7_22-12-13.png


Homework Equations

The Attempt at a Solution


I have split the system into two, creating a triangle. From this I have a right angle triangle with an adjacent of 2m, opposite of 0.6m and an hypotenuse of 2.088m (calculated through pythag). I have then worked out the angle at the pulley as 16.7 degrees. However I do not know how to now find W, I think it may have something to do with the equation 40kg x g x cos(90-16.7) + 40kg x g x sin(90-16.7), but this isn't given me the kind of answer I expected so I'm not sure if it's right.
upload_2015-12-7_22-25-10.png


Any help on the next step would be much appreciated!
 
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How about analyzing the forces acting at the point where the ropes connect to the 80 kg mass. Apply the conditions for equilibrium.
 
Doc Al said:
How about analyzing the forces acting at the point where the ropes connect to the 80 kg mass. Apply the conditions for equilibrium.
Am I right in thinking the forces are acting like this?
upload_2015-12-8_23-55-4.png
 
Wilson123 said:
Am I right in thinking the forces are acting like this?
Yes, that's exactly right. And if you set up the equilibrium equations, you can solve for T.