How to Determine Forces in Members BC and CG Using the Section Method?

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SUMMARY

The discussion focuses on determining the forces in structural members BC and CG using the section method in statics. The key equations utilized are ΣF=0 and ΣM=0, which are fundamental for analyzing forces in static systems. A common error identified is the miscalculation of applied forces, specifically confusing values such as 76 instead of the correct 78. Correctly applying these principles will yield accurate results for tension and compression in the members.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Familiarity with the section method in structural analysis
  • Knowledge of force sign conventions (tension vs. compression)
  • Basic proficiency in solving linear equations
NEXT STEPS
  • Study the section method in detail for structural analysis
  • Practice solving problems involving ΣF=0 and ΣM=0
  • Review common mistakes in force calculations in statics
  • Explore software tools for structural analysis simulations
USEFUL FOR

Students in civil or mechanical engineering, structural analysts, and anyone involved in solving static equilibrium problems in engineering contexts.

J-dizzal
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Homework Statement


Determine the forces in members BC and CG. The forces are positive if in tension, negative if in compression.[/B]
20150715_212522_zpsqjac02vi.jpg


Homework Equations


ΣF=0
ΣM=0

The Attempt at a Solution


20150715_212613_zpscgwqkzpn.jpg

I don't know where I am going wrong, My equations include the applied force, since there is only one.
 
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solved. I had some signs wrong and copied down 76 insted of 78.
 
Last edited:
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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