Statics: Finding the moment on point B?

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SUMMARY

The discussion focuses on calculating the moment about point B for three forces acting on a beam. The forces are defined as follows: F1 has a vertical component of 375 lb, F2 has components of -300 lb and -400 lb, and F3 has components of 138.6 lb and -80 lb. The perpendicular distances for F1, F2, and F3 are calculated based on their respective positions relative to point B, with F1 being 11 ft away. The moment is determined using the equation M = F*d⊥, where d⊥ represents the perpendicular distance from point B.

PREREQUISITES
  • Understanding of static equilibrium and moments in physics.
  • Familiarity with force decomposition into components.
  • Knowledge of the moment calculation formula M = F*d⊥.
  • Ability to interpret beam diagrams and distances in engineering contexts.
NEXT STEPS
  • Review the principles of static equilibrium in mechanics.
  • Learn about force decomposition and vector analysis in physics.
  • Study the application of the moment calculation in different engineering scenarios.
  • Explore beam loading conditions and their effects on structural analysis.
USEFUL FOR

Students studying engineering mechanics, particularly those focusing on statics and structural analysis, as well as professionals involved in mechanical and civil engineering applications.

Vanessa Avila
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Homework Statement


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[/B]
Determine the moment about point B of each of the three forces acting on the beam.

Homework Equations


M = F*d⊥

The Attempt at a Solution


I went and found the components for each of the forces. Please double check it if I did them right:

F1 :
Fx = 0
Fy = 375 lb

F2:

Fx = -500(3/5)lb = -300lb
Fy = -500(4/5)lb = -400lb

F3:
Fx = 160cos30° = 138.6lb
Fy = -160sin30° = -80lb

If those components are right, I'm having trouble finding their perpendicular distances.
 
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Based on the figure above is the
F*d⊥ for each of the forces are (without the sign convention/right hand method applied):
F1
Fx1 = 0
Fy1 = 375lb*19ft

F2
Fx2 = -300lb(0.5ft)
Fy2 = -400lb(19ft)

F3
Fx3 = 138.6lb(0.5ft)
Fx3 = -80lb(19ft)

I got 19ft by adding the three dimensions below the beam. Is that correct?
 
Label forces with F, and moments (force times distance) with M.
To calculate the moment of force F1 about point B, how far is F1 from point B?
 
David Lewis said:
Label forces with F, and moments (force times distance) with M.
To calculate the moment of force F1 about point B, how far is F1 from point B?
Ahh! 11 ft!
 

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