Rigid Body Equilibrium problem (no calculus)

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Homework Help Overview

The problem involves a gymnast on a beam supported by two posts, requiring the calculation of forces exerted by each support. The scenario includes specific weights and distances, focusing on rigid body equilibrium principles without the use of calculus.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the principle of moments as a method to find forces at the supports, questioning how this approach aids in determining specific forces. There are inquiries about the definition of lever arms and the forces involved, including whether to consider both the gymnast and the beam in calculations.

Discussion Status

The discussion is active, with participants exploring different methods to apply the principle of moments. Some have offered guidance on taking moments about supports, while others are seeking clarification on the concepts of lever arms and forces involved.

Contextual Notes

Participants are navigating assumptions about the setup, including the treatment of the gymnast as a particle and the implications of the beam's mass in the calculations. There is an emphasis on the need for two equations to solve for the two unknown forces.

minhaitran
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Homework Statement



Consider a gymnast on a bean placed on upright posts. The beam has a mass of 10kg and the gymnast has a mass of 50kg. The beam is 5 meters long, and the gymnast is 1 meter from the right side. The gymnast may be treated as a particle.

Find the force exerted by each support on the beam. There are two unknowns in the problem, and thus we need two equations.
 
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Principle of moments. Take moments about each support - the force exerted by that particular support would thus be excluded from consideration.
 
Fightfish said:
Principle of moments. Take moments about each support - the force exerted by that particular support would thus be excluded from consideration.

So how will that help me find the force on that support?
 
You can either:
1) Take moments about each support (which will yield the normal force on the other support) or
2) Take moment about one support to get the answer for the other support, and then use translational equilibrium criteria to obtain the force on the first support
 
I have a very similar problem.
In this case, what is the lever arm? I know torque = lever arm x force. Is the force the gymnast, or both the gymnast and the beam? Is the beam the lever arm?
 

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