Free Body Diagram from Space Diagram

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Discussion Overview

The discussion revolves around converting a space diagram into a free body diagram, focusing on identifying and representing forces acting on specific points in a mechanical system. The context is primarily homework-related, involving the application of concepts from statics and mechanics.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses uncertainty about the inclusion of moment forces and the correctness of reaction forces at points J and E.
  • Another participant clarifies that the wheel at point J prevents horizontal reactions, indicating that only vertical forces are present there.
  • It is noted that pin E supports both horizontal and vertical forces, but a participant argues that no horizontal force is applied to the structure, suggesting that only vertical forces should be considered at E.
  • Participants discuss the direction of the vertical reactions at points J and E, with the assertion that both will point upwards due to the downward forces acting on the structure.

Areas of Agreement / Disagreement

There is some agreement on the types of forces at points J and E, but disagreement exists regarding the presence of horizontal forces at E and the necessity of moment forces. The discussion remains unresolved on these points.

Contextual Notes

Participants have not fully resolved the assumptions regarding the application of forces and the need for moment forces in the free body diagram. The discussion reflects varying interpretations of the forces based on the provided space diagram.

steve2510
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Homework Statement



http://desmond.imageshack.us/Himg804/scaled.php?server=804&filename=img1.gif&res=medium
I have to change this space diagram into a free body diagram and i am struggling

Homework Equations





The Attempt at a Solution



I have put a reaction force in the the x direction at point J and a rection force in the y direction at point j aswell. I have also done the same at Point E. I don't no if this is right? I'm not sure if there is meant to be a moment force somewhere? Could anyone help?
 
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The purpose of the wheel at J is to prevent any horizontal reaction at that point, so the only external force there is vertical. Now at E, the pin will support both a horizontal and vertical force, but no moment, so forces in both directions there are correct.
 
thanks very much !
 
Are you only asked for a free body diagram?

Because, it's also important you get the vectors direction right, and this you can normally only do with calculations.

While in principle pin E supports both a horizontal and a vertical force, you can see that no horizontal force is applied at the structure. So there is no horizontal force there at E.

Also, you can see that both vertical reactions at J and E will point up, because all the other forces in between them point down.
 

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