Determine the resultant couple moment

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Discussion Overview

The discussion revolves around determining the resultant couple moment acting on a beam, specifically addressing the confusion regarding the signs (positive or negative) associated with the moments calculated from applied forces. The context is a homework problem involving the application of forces and their distances.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant states that clockwise (CW) moments are considered positive and counterclockwise (CCW) moments are negative, but expresses confusion about when to apply these signs in calculations.
  • The same participant attempts to clarify their understanding by providing a formula for calculating moments, but questions why both calculated moments are treated as positive in their specific case.
  • Another participant suggests that the textbook might explain the concept, possibly referencing the right-hand rule as a method for determining moment direction.
  • A later reply from the original poster expresses frustration at the lack of explanation in the textbook and requests a more helpful response rather than a question.
  • One participant provides a link to an external resource about the right-hand rule, implying it may help clarify the confusion regarding moment direction.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the application of positive and negative signs in moment calculations, as the original poster remains confused and seeks further clarification.

Contextual Notes

The discussion highlights a lack of clarity in the textbook regarding the application of moment signs and the right-hand rule, which may contribute to the confusion experienced by the original poster.

joker2014
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Homework Statement



4-70 Two couples act on the beam. If F=125 lb. determine the resultant couple moment.
media%2F385%2F3854ab81-8861-4c80-a860-cad551f28f07%2FphpFDUPHk.png

Homework Equations



M=Fd

The Attempt at a Solution


I know CW is + and CCW is - ...and that is determined in the final answer,
I know the solution is taking Forces times the distance, the solution is M=(200*1.5)+(125cos30*1.25)

question is why are they both positive? when do we consider taking negative instead positive? I've seen other solutions for other questions, where they take negative ... I am confused when to take negative or position... so why not -200 or -125 [/B]
 
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Are you sure your textbook doesn't explain this? Like mentioning the right hand rule?
 
it didnt, otherwise i wouldn't ask here... you could have did me favor and explained rather than asking me a non sense question.. thank you anyways.
 
joker2014 said:
it didnt, otherwise i wouldn't ask here... you could have did me favor and explained rather than asking me a non sense question.. thank you anyways.
I dropped a rather big hint.

https://en.wikipedia.org/wiki/Right-hand_rule
 

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