Massless beam held against a wall

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Homework Help Overview

The problem involves a massless beam held against a wall by a massless string, with a 2000N mass attached at the end. The setup includes parameters such as the length of the beam (L) and the angle (θ) above the horizontal, but the original poster notes a lack of sufficient information to solve for the tension in the string, the angle, and the forces exerted by the wall.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the adequacy of the provided information, with some suggesting that the problem may not be completely unsolvable by setting up equations for forces and torques. Others question the implications of the beam being held against the wall and the conditions under which it operates.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem setup and questioning the assumptions made about the beam's interaction with the wall. Some guidance on potential equations to consider has been offered, but no consensus on the solvability of the problem has been reached.

Contextual Notes

Participants note the ambiguity in the problem's description, particularly regarding the nature of the beam's support against the wall and the implications of it being massless. There is also mention of the difficulty in determining the angle θ without additional information.

bboytymee
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Homework Statement


Just took my finals and there was one problem that bugged me, I have done these types of problems multiple times and understand it well but this particular problem seems like there isn't enough information.

There is a massless beam being held against a wall by a massless string. A 2000N mass is attached to the end of the beam. The beam is L meters in lenght. The distance from the string on the wall to the end of the beam touching the wall is L. The beam is θ degrees above the horizontal.
a) Find the tension in the string
b) Find the angle θ
c) Find the horizontal and vertical force being exerted on the massless beam by the wall.

Basically the only value you have is 2000N, and you know that the distance of the beam and the distance of the wall is equal, and therefore it forms an isosceles triangle.

I couldn't find a picture of the problem but the set up is similar to this
http://s3.amazonaws.com/answer-board-image/cddfc98e-12fc-48cb-9ef4-c645d675f561.jpeg
except the bar is tilted at angle θ, the length of the bar is L.

Homework Equations


τ=Flcosθ

The Attempt at a Solution



I understand the equations and isolation of systems completely, the only thing that is restricting me from solving the problem is finding the value of θ so I was wondering if anyone who is really good at trig could help.
 
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There is clearly not enough information here. Are you sure you have this verbatim?
 
I thought so, yes this is verbatim. All of my peers in class wern't able to solve it either so I'm sure there isn't enough information. Just wanted to see if someone with higher knowledge thought the same.
 
It doesn't seem completely unsolveable. I've done similar problems. Let's see what equations we can set up... forces in y direction (equal to 0), forces in x direction (also 0), balancing of torques (also 0) and maybe some trig equations: addition of angles and the law of cosines *could* possibly help.
 
One thing that intrigues me is this phrase: "being held against a wall by a massless string". What exactly does that mean? Only one end of the beam touches the wall. It almost suggests it's just resting against the wall rather than hinged, but there would have to be some friction or the beam would slip (unless theta=0), so it might as well be hinged. Maybe it is supposed to be frictionless and hingeless, in which case it is easy to solve.
 

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