Moment in different dimensions in 2 D

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Homework Help Overview

The discussion revolves around a statics problem involving moments in two dimensions, specifically focusing on the reactions at supports B and C in the presence of a 60 N·m moment. Participants are exploring the implications of this moment's direction and its interaction with other forces in the system.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants are questioning whether the 60 N·m moment should be added to the moments created by other forces, considering the directionality of the moments involved. There is a debate about the mechanical interpretation of the moment's effect on the structure.

Discussion Status

The discussion is ongoing, with various interpretations being explored regarding the moment's direction and its mechanical implications. Some participants suggest that the wording of the problem may not clarify the intended direction of the moment, leading to confusion about how to approach the calculations.

Contextual Notes

There is mention of potential ambiguity in the problem's wording and diagram, with participants noting that the moment may not be clearly defined in the context of the question. Additionally, there is speculation that the problem may have been adapted from a textbook, which could contribute to the confusion.

abdo799
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Homework Statement


This isn't exactly a HW question, it's a question in my statics midterm today, he wants the reactions at the supports B and C, which is easy but the problem is this 60 N.m moment, all my friends were like :" let's just sum the moments around B ( due to the 50 N and the reaction at C) and just add this 60 N.m, but when i tried it , the reaction at C was 1100 N , which is kinda huge , plus , i don't think we can just add them , as the dimension of the moment created by the 50 N and the reaction at C is in the k direction while the 60 N.m ( using the right hand rule) should be in the i direction, so i don't think we can just add them up
so, who's right? add them or don't add them?

Homework Equations

The Attempt at a Solution

 

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While the diagram does make it look as though the 60N.m is twisting the structure out of the page, that doesn't make much sense mechanically. There is no countering torque. So I suspect it is intended to be in the k direction. Any wording in the question that might clarify?
 
the wording was , find the reaction at B and C if a = 1.5
makes no sense if this was in the k direction, because, why would he even draw it there, the moment in the K direction is drawn 99% of the times around one of the supports
 
abdo799 said:
the wording was , find the reaction at B and C if a = 1.5
makes no sense if this was in the k direction, because, why would he even draw it there, the moment in the K direction is drawn 99% of the times around one of the supports
Are you saying the text does not mention this extra 60 N.m torque at all?
I agree there is no interpretation that makes much sense. It could be intended to be some external torque about B, but in that case it is drawn strangely and I would expect it to be mentioned in the description. If it is in the k direction it swamps the 1.5 N.m from the load at A. I'd be inclined to dismiss it as either a mistake in the diagram or (as a torque in the i direction) as a deliberate red herring.
 
my interpretation is : this question is from a textbook , where they often use the same figure for different questions, maybe it's used in another question, in the exam, i tried to add it, made no sense with the 1100 N reaction at C
 

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