please help! mechanics: Friction question Watch

awfiya
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A bead B of mass 0.9 kg is threaded on a light inextensible string of length 70 cm. The string is fixed at one end A with the other end attached to a ring R of mass 0.5 kg, threaded on a fixed rough horizontal rod. The system is in limiting equilibrium when R is 50 cm from A.
The coefficient of friction between the ring and the rod is 0.3.
find the tension in the strin given that the ring is about to slip
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Gome44
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Do you have a diagram or something?
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awfiya
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(Original post by Gome44)
Do you have a diagram or something?
Name:  friction.png
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Gome44
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Do you have the answer? I got T=2.97 to 3 sf but i didn't use half the information?
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awfiya
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(Original post by Gome44)
Do you have the answer? I got T=2.97 to 3 sf but i didn't use half the information?
yeah you got it right!!
Can you please explain?
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Gome44
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Scrap that, i got 2.91 to 3 sf
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Gome44
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is that still right?
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awfiya
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(Original post by Gome44)
Scrap that, i got 2.91 to 3 sf
Actually the answer is T=2.98. can you explain how you got whatever answer you got??
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Gome44
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Sorry, but i think i was lucky to get that answer.

What i did was work out the angle ARB using the cosine rule, and then considered only the ring R
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awfiya
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(Original post by Gome44)
Sorry, but i think i was lucky to get that answer.

What i did was work out the angle ARB using the cosine rule, and then considered only the ring R
oh that's okay, thank you for reviewing my question
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zino
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I can't seem to draw the forces (reaction at pulley, friction) correctly. I have found cosα to be 5/7 but can't find the answer as my ΣF=0 equations are wrong. Can you guys explain please? Thanks
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ghostwalker
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(Original post by zino)
I can't seem to draw the forces (reaction at pulley, friction) correctly. I have found cosα to be 5/7 but can't find the answer as my ΣF=0 equations are wrong. Can you guys explain please? Thanks
The information as supplied by the OP, doesn't seem consistent.

Do you have a link to the actual question, or a scan/photo?

Failing that, can you provide the question, exactly as worded.
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