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The discussion revolves around calculating the mass in a system described as being in equilibrium, with a focus on the relationship between forces and torques. Participants confirm that the system is massless and pivoted at a right angle, leading to the conclusion that the sum of moments about the pivot must equal zero. The tension in the diagonal member is expressed in terms of mass and angle, but there is uncertainty about calculating tension without knowing the mass. The importance of setting up the equilibrium of forces alongside torques is emphasized for a complete solution. Overall, the conversation highlights the need for clarity on both forces and torques to solve for mass effectively.
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Homework Statement


Find the mass:
FindMass.jpg


Homework Equations


Not Sure.


The Attempt at a Solution


I don't know where to start as I believe that there is less information.

All that I have got upto is Tan-1(3/8) but I don't know if this is needed to find the mass? :confused:
 
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I'm assuming the frame is massless, pivoted bout the right angle of the triangle and the system is in equilibrium, am I correct?
 
Hootenanny said:
I'm assuming the frame is massless, pivoted bout the right angle of the triangle and the system is in equilibrium, am I correct?

Yes, You are correct.
 
So, we know that since the system is in equilibrium, the sum of the moments about any point should be zero. However, let's consider the forces; if the system is not translating (i.e. moving up or down) what must be the vector sum of the vertical forces?
 
Hootenanny said:
So, we know that since the system is in equilibrium, the sum of the moments about any point should be zero. However, let's consider the forces; if the system is not translating (i.e. moving up or down) what must be the vector sum of the vertical forces?

Erm...Not sure but guessing zero. :redface:
 
Sounds good to me :smile: and where will this reation force be applied?
 
Hootenanny said:
Sounds good to me :smile: and where will this reation force be applied?

Either at the angle at the end of Y or near the mass?
 
Normal forces are applied at the point where the system pivots. Just checking, is the side x attached to a wall of some kind?
 
Hootenanny said:
Normal forces are applied at the point where the system pivots. Just checking, is the side x attached to a wall of some kind?

Nope. The pivot is at the corner of x and y.

x and y dimensions are given if to calculate the angle (I think).
 
  • #10
Okay, let us consider the torques about the pivot point;

0.08T\sin\left(\arctan\left(\frac{3}{8}\right)\right) = 0.4mg

Where T is the tension in the diagonal member. Do you follow?
 
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  • #11
Hootenanny said:
Okay, let us consider the torques about the pivot point;

0.08T\sin\left(\arctan\left(\frac{3}{8}\right)\right) = 0.4mg

Where T is the tension in the diagonal member. Do you follow?

Yes, I do. :smile:
 
  • #12
Hootenanny said:
Okay, let us consider the torques about the pivot point;

0.08T\sin\left(\arctan\left(\frac{3}{8}\right)\right) = 0.4mg

Where T is the tension in the diagonal member. Do you follow?

Can Tension be calculated without mass? :confused:
 
  • #13
You still have not set up the equalibrium of FORCES, only of torques..

Also, for your information,
\sin(\arctan(x))=\frac{x}{\sqrt{1+x^{2}}}
 
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