Rotation around center of mass principle

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SUMMARY

The principle of rotation around the center of mass (CM) dictates that when torque is applied to a free object, it will invariably rotate around its center of mass rather than an arbitrary point. This phenomenon occurs because rotation about the CM minimizes energy expenditure, making it the most stable position for an object. Additionally, rotating around a point other than the CM often leads to instability, particularly in cases of unbalanced rotation. Understanding this principle is crucial for applications in physics and engineering.

PREREQUISITES
  • Understanding of torque and its effects on rigid bodies
  • Familiarity with the concept of center of mass in physics
  • Basic knowledge of rotational dynamics
  • Awareness of energy conservation principles in mechanical systems
NEXT STEPS
  • Research the mathematical derivation of torque and its relationship to center of mass
  • Explore the implications of rotational stability in mechanical engineering
  • Study examples of unbalanced rotation and their effects on stability
  • Learn about energy minimization principles in physical systems
USEFUL FOR

This discussion is beneficial for physics students, mechanical engineers, and anyone interested in understanding the dynamics of rotating bodies and stability in mechanical systems.

arto460
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Hey all!
I always use this principle when I do exercises, but today I found out, that I can't explain why it's valid. What I'm talking about is that when you apply a torque to a free object it will always start to rotate around it's center of mass rather than just an arbitrary point. Why is that? I know that rotation around the cm requires the least energy so if there was some fundamental theorem saying that a system always tends towards the least increase in energy or whatever, that might explain it.
Yet I don't think that's the way to go, so can someone explain it please?
 
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I never really questioned it myself but I think it has to do with rotation about the center of mass being the most stable position. Otherwise rotating about another axis (which is not the center of mass) usually causes high instability.

An example is rotating unbalance.
 

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