How to find moment of inertia of an insect?

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    Inertia Insect Moment
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Discussion Overview

The discussion revolves around finding the moment of inertia of an insect, specifically a cockroach, in the context of analyzing torque. Participants explore various methods and considerations for calculating this value, including the use of general formulas and modeling techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant suggests using the general formula for moment of inertia but acknowledges that shortcuts may exist depending on the required precision and available information.
  • Another participant provides context, stating they are analyzing torque on a cockroach and have data on angular acceleration, mass, and dimensions.
  • Concerns are raised about the applicability of the general formula due to the cockroach's complex shape, prompting inquiries about alternative modeling approaches.
  • A participant links to a resource that discusses cockroach morphology and suggests that understanding the provided model could help refine the user's approach.
  • Another suggestion is made to model the cockroach as two partial ellipsoids and to consider numerical methods for calculating the moment of inertia.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the applicability of the general formula for moment of inertia due to the cockroach's complex shape. Multiple modeling approaches are proposed, indicating that there is no consensus on a single method to use.

Contextual Notes

Participants note limitations related to the complexity of the cockroach's shape and the potential need for numerical methods or modifications to existing models. There are unresolved questions about the adequacy of the general formula in this specific case.

Who May Find This Useful

This discussion may be useful for students or researchers interested in biomechanics, physics of motion, or those conducting projects related to insect physiology and mechanics.

potatoboy
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Hello, I am curious to find the moment of inertia of an insect.
My guess is that I use the formula

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to find the moment of inertia.

I would appreciate any help.
 
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That is the general formula for computing moment of inertia, yes, although there are a number of shortcuts you can take depending on how precise an answer you need and what information you have.

What's the context for the problem? Why do you want to know?

And what information do you have about your insect?
 
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Hello,
In summary, I'm doing a project on analyzing torque on a cockroach.

I have gathered data on angular acceleration of my cockroach and in order to find torque, I am required to find the moment of inertia. I have the mass and dimensions of the cockroach in g and cm respectively.

Due to the complex shape of the cockroach, I am curious if I am able to just use the general formula for it.

If you do have any suggestions, I am open to anything. :smile:
 
I'd read the article PeroK linked first. If the model there works for you, great. If not, then understanding why it doesn't work will help to refine what you need to put into your own model.
 
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potatoboy said:
Due to the complex shape of the cockroach, I am curious if I am able to just use the general formula for it.
You could model the body as two partial ellipsoids. The moment of inertia derivation for a full ellipsoid is linked below. Maybe you can modify it to get just a part.

https://scienceworld.wolfram.com/physics/MomentofInertiaEllipsoid.html

Or you use the general formula and do it numerically.
 
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