This is an engineering statics question, I on trig

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Discussion Overview

The discussion revolves around an engineering statics problem involving the determination of forces acting on a system of cylinders, specifically focusing on the relationship between the weights and angles involved. The context includes the application of static equilibrium equations and trigonometric relationships.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant states the problem involves finding the weight of cylinder F given the weight of cylinder E and an angle theta.
  • The participant provides their equations for static equilibrium: Sum(x) = 0 and Sum(y) = 0, but expresses difficulty in solving them.
  • Another participant suggests solving the first equation for F_{ab} in terms of F_{bc} to facilitate solving the second equation for F_{bc}.
  • A later reply questions the validity of using symmetrical properties of angles in the context of the forces acting on knot B, acknowledging the presence of another tension force complicating the assumption.
  • One participant expresses frustration with their understanding of trigonometry despite being in advanced calculus and physics courses.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus on the approach to solving the equations, with participants offering different suggestions and expressing uncertainty about the application of trigonometric properties in the context of the problem.

Contextual Notes

Participants acknowledge limitations in their understanding of trigonometric relationships and the implications of multiple forces acting on the system, which may affect their ability to solve the equations correctly.

GreenAce92
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1. If cylinder E weighs 30lb and theta = 15 degrees, determine the weight of cylinder F
2. Sigma F = 0 (Statics question)
3. I have gotten my separate components but I don't know how to solve the equations this sounds really stupid since I'm in calc III and physics II but my brain is just crapping out on me.

I have attached a sketch of the problem
The only thing(s) that are given are the three angles, and one weight.

I am having a hard time figuring out how to solve these equations.

So far I have
Sum(x) = 0 = -Fab cos30 + Fbc cos15
Sum(y) = 0 = Fbc sin30 - 30 - Fab sin15

I even have the solutions on hibbeler however I want to learn how to solve these equations, its definitely a basic concept that I should know how to do, that is solving trig problems.
 

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Can you solve the first equation for F_{ab} in terms of F_{bc}? Once you do that, you should be able to plug that into the second equation and solve for F_{bc}.
 
Even with opposite signs /components?
I will try
Thank you

Question:
For the FBD on knot B
Can I not use the properties of angles that are symmetrical about a line segment to assume that Fcb cos 15 = 30cos15?

Actually in the physical sense that's not correct seeing as there is another tension force on the other side of knot b.
 

Attachments

  • Problem,.png
    Problem,.png
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Last edited:
I think I've got it, I just hit a dumb wall of "I can't do trig even though I'm in calc III"
 

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