Comments about "Center of mass" in Wikipedia

This document contains comments about the document "Center of mass" and Center of Gravity in Wikipedia
In the last paragraph I explain my own opinion.



The article starts with the following sentence.
In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero or the point where if a force is applied causes it to move in direction of force without rotation.
This definition is unclear. See Reflection Center of Mass" versus "Center of Gravity"
The last part of the sentence makes only sense if one object is involved.
In the case of a distribution of separate bodies, such as the planets of the Solar System, the center of mass may not correspond to the position of any individual member of the system.
In this case you should speak of the "center of gravity".

1. Implications

2 Justification

3. Background

4. References

7. See also

Following is a list with "Comments in Wikipedia" about related subjects

Reflection Center of Mass" versus "Center of Gravity"

In general for applications where only one object is involved we can speak of a center of mass. For a round flat object this is at the center.
For applications where more objects are involved we can only speak of a center of gravity. This is specific the case for all astrophysical objects. The barycenter coincides with the center of gravity.
The main reason for this clear distinction is because in astronomy the mass of an object can only be calculated starting from the concept of gravitational forces. Next at each instant the center of gravity can be calculated. Finally the masses can be calculated (if not known). This can only be done if the objects considered are observed for "a long period".
See also Visual Basic program: VB Two_body


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Created: 1 February 2016

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