Why does the centre of gravity shift when a rod is displaced?

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Discussion Overview

The discussion revolves around the behavior of a rod (or plank) and its center of gravity when displaced. Participants explore the implications of this displacement on normal reactions and seek both quantitative and qualitative explanations for the observed changes in equilibrium.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant notes that when the rod is displaced, the normal reactions change, with one being greater than the other, prompting a question about the underlying reason.
  • Another participant suggests writing down the torque equation for the plank about its center of gravity (G) to understand the situation better.
  • A later reply confirms that using the torque equation provided clarity but seeks a qualitative explanation for the shift in center of gravity and its effect on normal reactions.
  • One participant expresses uncertainty about providing a qualitative explanation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a qualitative explanation for the shift in center of gravity or the changes in normal reactions, indicating that multiple views and uncertainties remain.

Contextual Notes

The discussion lacks detailed assumptions about the system's configuration and the definitions of terms like center of gravity and normal reactions. There are also unresolved aspects regarding the torque calculations and their implications.

andyrk
Messages
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In the first attachment, the normal reactions are equal. But when the rod is displaced a slight distance x towards the right (second attachment), the normal reactions change to R1 and R2 with R2 being greater than R1. Why is that?
 

Attachments

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Hi andy

The plank and the cylinders are in rotational equilibrium . Can you write down the torque equation for the plank about G ? This should give you the answer you are looking for :smile: .
 
Tanya Sharma said:
Hi andy

The plank and the cylinders are in rotational equilibrium . Can you write down the torque equation for the plank about G ? This should give you the answer you are looking for :smile: .
Yes it worked. Thanks for that. But is there a qualitative explanation to it too? Something like: The CG shifted which made more mass come on top of one cylinder than the other...? Similarly, is there some qualitative explanation to why the normal reactions are equal when the plank is not displaced?
 
I don't know :oldsmile:
 

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