How can equilibrium of a rigid body be determined using the given information?

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Homework Help Overview

The discussion revolves around determining the equilibrium of a rigid body, specifically a rod in contact with a floor and a peg. Participants are exploring the forces acting on the rod and how to analyze them in the context of equilibrium conditions.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to understand the normal reaction forces acting on the rod and questions their directions. They express uncertainty about the relationship between the normal force and the weight of the rod.
  • Some participants suggest drawing a free body diagram to visualize the forces and clarify the normal force's direction, while also emphasizing the importance of considering all forces acting on the rod.
  • Others raise the need to account for multiple normal forces, including one at the peg, and discuss the conditions for equilibrium, such as the requirement for the resultant torque and force to be zero.

Discussion Status

The discussion is active, with participants providing guidance on how to approach the problem. There is a focus on clarifying the roles of different forces and the necessity of a comprehensive analysis to achieve equilibrium. Multiple interpretations of the forces involved are being explored, indicating a productive exchange of ideas.

Contextual Notes

Participants are working within the constraints of a homework problem, which may limit the information available for analysis. There is an emphasis on understanding the setup and assumptions related to the forces acting on the rod.

FearOfFM
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Homework Statement


[PLAIN]http://img24.imageshack.us/img24/8382/fm1u.png

Homework Equations


µ ≥ tan Θ

The Attempt at a Solution


I'm new here, if I post something wrong here. please correct me! :)
I don't understand the question.
Where is the normal reaction between the rod and the floor? from figure 1.
Is it in the same direction as the rod acting on the floor? or perpendicular to the floor?
If the normal reaction is same as the direction as the rod acting on the floor then:
Resolve vertically - R cos Θ = W
Resolve horizontally - R sin Θ + F = ?
F ≤ µR
F ≤ µW / cos Θ ? is it correct?
 
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FearOfFM said:

I don't understand the question.
Where is the normal reaction between the rod and the floor? from figure 1.
Is it in the same direction as the rod acting on the floor? or perpendicular to the floor?



The normal force is always normal to the surface. Draw the free body diagram with all forces acting on the rod. The normal force from the floor acts upward.

ehild
 
ehild said:
The normal force is always normal to the surface. Draw the free body diagram with all forces acting on the rod. The normal force from the floor acts upward.

ehild

Thanks ehild... :)
so resolve vertically R = W :)
I will try to work out this question. I will be back~!
 
FearOfFM said:
so resolve vertically R = W :)

It is not that simple. Draw all forces. There is a normal force also at the peg.The resultant torque and the resultant force both have to be zero at equilibrium.

ehild
 
Last edited:
ehild said:
It is not that simple. Draw all forces. There is a normal force also at the peg.The resultant torque and the resultant force both have to be zero at equilibrium.

ehild

I forgot there is a normal force at the peg >.<!

so R1 + R2 = W
and how to resolve horizontally?
 
The reaction force from the floor is vertical, but that of the peg is not. The forces are vectors, you have to add both the horizontal and vertical components.
What forces act horizontally?

ehild
 

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