Simple quesiton involving Tension of a cable supporting a beam

AI Thread Summary
The discussion revolves around calculating the tension in a cable supporting a beam with a weight of 90 kg. The tension throughout the rope is assumed to be uniform, leading to the equation ∑Ma=0, which results in a calculated tension of 933.383 N. The participants confirm that using point A as the pivot simplifies the problem by eliminating the need to consider reaction forces at that point. There is some confusion regarding the signs in the equation, specifically why one tension value is negative. Overall, the focus is on understanding the mechanics of tension in the cable system.
mike41
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Homework Statement



Prob.5-4.jpg

Determine the tension in the cord if the weight is 90kg

The Attempt at a Solution



The tension is the same throughout the rope apparently so;

∑Ma=0
= T(2) - (4/5)T(4) - 882.9N(5.5)
T= 933.383N...

would that be the force in the cable then? i don't have to worry about Ay or Ax because that is my pivot point then right?
 
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Hi mike41! :wink:
mike41 said:
i don't have to worry about Ay or Ax because that is my pivot point then right?
Yes, you choose A as the point to take moments about precisely because you don't want to be bothered with the reaction forces at A. :smile:
The tension is the same throughout the rope apparently so;

∑Ma=0
= T(2) - (4/5)T(4) - 882.9N(5.5)
T= 933.383N...

would that be the force in the cable then?

erm … why is one T minus? :redface:
 

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