Equilibrium Force: Solving for Centre of Mass | Homework Statement

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The discussion centers on solving for the center of mass in a static equilibrium scenario involving a pole and a box. Participants clarify that the phrase "the pole and the box do not change form" indicates that the center of gravity remains constant. It is suggested that person A will carry more weight due to their higher position, and the relevant equations for static equilibrium include the conditions for no net force and no net torque. The conversation emphasizes that in static situations, all forces must balance, and the forces acting on the system are vertical. The problem highlights the importance of understanding force distribution in practical scenarios like carrying objects.
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Homework Statement



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Homework Equations

The Attempt at a Solution


I'm not sure about which topic it is asked. I think it's something about the centre of mass . Because the statement " The pole and the box do not change form" . The answer is
(1 + tan Θ)/(1 - tan Θ)
 
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What are (all!) the relevant equations for static equilibrium ?

Who do you think will have to carry more in the right picture ? B or A ? Why ?

The "don't change form" remark is to reassure you the center of gravity stays in the same place in the box/pole combo.
 
BvU said:
What are (all!) the relevant equations for static equilibrium ?

Who do you think will have to carry more in the right picture ? B or A ? Why ?

The "don't change form" remark is to reassure you the center of gravity stays in the same place in the box/pole combo.

A will carry more, I think it's because he's in higher position.
And is there any special formula for static equilibrium ? I just draw a triangle and use the formula F=ma.
 
Hehe, you never had to carry something heavy down the stairs, I suppose ?

The conditions for equilibrium I hinted at in post #1 are in the first place ##\Sigma \vec F = 0## So that with your formula a = 0 ##\Rightarrow## v = constant. v = 0 remains v = 0. No translation.

But that's not enough. You also want no rotation, in other words: ##\Sigma \vec \tau = 0##.
And now the positions where the forces act come in the expressions.
 
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CH Lee said:
A will carry more, I think it's because he's in higher position.
And is there any special formula for static equilibrium ? I just draw a triangle and use the formula F=ma.

F = ma comes into question when acceleration comes into question. Here, a = 0 and v = 0. All forces balance each other out. FA and FB act vertically upward. In which direction do you think 'W' acts?
 
The forces are vertical. That is a constraint on the answer given by the question statement. In an actual case of carrying a couch down a ramp the people doing the carrying probably would not arrange their hand-holds that way, but the problem requires it.

The pole is not rotating while it is being carried.
 

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