Finding moments in pedal (beam w/ rightangles)

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    Moments Pedal
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Discussion Overview

The discussion revolves around calculating moments and forces in a horizontal beam (pedal) with a hinge and a support, where a person stands on the beam. Participants explore the mechanics involved, particularly focusing on the vertical forces and moments at various points of the beam, including the confusion surrounding the vertical component at a specific section of the beam.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant seeks advice on finding moments on a horizontal beam with specific dimensions and a load applied at one point.
  • There is confusion regarding how to account for vertical forces at a horizontal section of the beam, particularly at point CD.
  • Some participants suggest completing a free body diagram (FBD) to clarify the forces and moments acting on the beam.
  • Questions are raised about the nature of the support at point B, whether it is a spring or a rope support, and how this affects the calculations.
  • Participants inquire whether the force at point E remains perpendicular to the beam as it rotates, which is relevant for determining moments.
  • There is a request for the participant to show their equations for the sum of forces and moments from the FBD to facilitate further discussion.
  • One participant expresses a desire to learn the underlying principles rather than just receiving answers, indicating a focus on understanding rather than simply solving the problem.

Areas of Agreement / Disagreement

Participants generally agree on the need to clarify the forces and moments through a free body diagram, but there is disagreement and confusion regarding the treatment of vertical forces at specific points on the beam. The discussion remains unresolved as participants explore different aspects of the problem.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the forces acting on the beam, particularly concerning the vertical component at CD and the nature of the support at B. The participants have not reached a consensus on how to approach these aspects.

Letsgetphysicscool
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hello friends i am seek advice on a engineer question (sorry if grammar bad english isn't my first language but i learn)

i require to find the moments on a pedal. the pedal is horizonta. as the picture provided the hinge point is at a and there is a support at b. at e a man stands and is 750 Newton and dimension ab = 375 bc=140 cd=150 de=380 ef=70. all angles are 90 degrees.
bitmap.png


i know how resolve if it had no vertical on beam but vertical at cd is confuse. what is the best way to tackle this problem? i wish for speedy conclusion i want to learn not be told answer
what i know is i have clockwise moment across the beam because a is hinge point so forces to resolve on rightward side

do i structure the problem in three parts with diagrammes follow?
then calculate the vertical reaction forces on a and b i am only to consider the dimensions of abc and def and the dimension cd is a mislead?

thank kindly
 
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Welcome to PF. :smile:

Yes, you need to finish the FBD that you've started above. Note that the force you show at the hinge point A is opposite to the direction I would expect for countering the torque due to the person standing on the structure.

Also, is this for schoolwork? If so, we can move it to the schoolwork forums for you.
 
berkeman said:
Welcome to PF. :smile:

Yes, you need to finish the FBD that you've started above. Note that the force you show at the hinge point A is opposite to the direction I would expect for countering the torque due to the person standing on the structure.

Also, is this for schoolwork? If so, we can move it to the schoolwork forums for you.
thank you friend. i replaced the diagramme for a newer one.

so calculate the vertical reaction forces on a and b i only consider the dimensions of abc and def (vertical on the beam) and not cd (horizontal on the beam)?
 
Is the support at B a spring?
Does the force at E remain perpendicular to the structure as it rotates?
E to F need not be considered if the downward force is concentrated at E.
 
AZFIREBALL said:
Is the support at B a spring?
Does the force at E remain perpendicular to the structure as it rotates?
E to F need not be considered if the downward force is concentrated at E.
thank you friend

b is not spring is a rope support from above beam not coming from below. and the beam with the hinge point a and load at point e it is in equalibrium. e is point load yes is perpendicular
 
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berkeman said:
Also, is this for schoolwork? If so, we can move it to the schoolwork forums for you.
@Letsgetphysicscool -- I don't think you've answered this question of mine yet...
 
And whether it is a schoolwork assignment or not, can you show us your sum of forces and sum of moments equations from the FBD? It's better if you use LaTeX to post the math equations instead of trying to fit them into ASCII simplifications (see the LaTeX Guide link below the Edit window). Thanks. :smile:
 
berkeman said:
And whether it is a schoolwork assignment or not, can you show us your sum of forces and sum of moments equations from the FBD? It's better if you use LaTeX to post the math equations instead of trying to fit them into ASCII simplifications (see the LaTeX Guide link below the Edit window). Thanks. :smile:
hello friend

this is what i stuck with and i say in first message. i confuse with vertical part on beam at cd otherwise i can do.

i don't know how to account for vertical part on horizontal.

is there general formula or rule? once i know this i can resolve for a and b
 

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