Why do we need a separate center of gravity idea when we have CoM?

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SUMMARY

The discussion centers on the distinction between the center of mass (CoM) and the center of gravity (CoG) in the context of non-uniform gravitational fields. It establishes that while the CoM behaves as a point particle under external forces, the CoG accounts for rotational effects and the application of gravitational forces. The CoG is particularly useful in scenarios where gravitational forces are not uniform, as it simplifies calculations related to torque and angular acceleration. The conversation emphasizes the necessity of both concepts in understanding motion and forces acting on a system of particles.

PREREQUISITES
  • Newtonian mechanics principles
  • Understanding of center of mass (CoM) and center of gravity (CoG)
  • Basic knowledge of gravitational fields and forces
  • Familiarity with torque and angular acceleration concepts
NEXT STEPS
  • Study the mathematical derivation of center of mass and center of gravity
  • Explore the effects of non-uniform gravitational fields on motion
  • Learn about torque and its relation to center of gravity
  • Investigate the concept of the point of application for external forces
USEFUL FOR

Physics students, mechanical engineers, and anyone involved in dynamics and motion analysis will benefit from this discussion, particularly those interested in the implications of gravitational forces on rigid bodies.

  • #31
kuruman said:
Isn't that what I have?
Sorry I was viewing it on mobile. I had to slide it to see it full
 
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  • #32
Ryder Rude said:
The center of mass point literally follows the path that a particle of mass M would've followed if the forces on the system were thought of as directly acting on that point.
If the center of gravity (or buoyancy or any other distributed force) is different from the center of mass then the force acts through the center of gravity (etc) and therefore produces a torque about the center of mass. The motion of the body then cannot be described simply by the path of the center of mass. The object will rotate about the center of mass. Modeling this torque is the reason for distinguishing the center of mass from the center of gravity (etc).
 
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