A paradox inside Newtonian world

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    Newtonian Paradox
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SUMMARY

The forum discussion centers around a paradox in Newtonian mechanics concerning gravitational forces and the center of mass. Participants debate the implications of gravitational interactions among a series of masses arranged in a specific configuration, particularly focusing on how these forces influence the motion of the center of mass. Key points include the assertion that the net force on a particle is directed to the left, despite the presence of larger masses on the right, and the challenge of reconciling this with Newton's Third Law. The discussion highlights the complexities of infinite series in gravitational calculations and the necessity of considering finite systems to resolve the paradox.

PREREQUISITES
  • Understanding of Newton's Laws of Motion, particularly Newton's Third Law
  • Familiarity with gravitational force calculations and mass distribution
  • Knowledge of infinite series and their implications in physics
  • Basic principles of mechanics and center of mass calculations
NEXT STEPS
  • Explore the implications of Newton's Third Law in gravitational systems
  • Study the behavior of infinite series in physics, particularly in gravitational contexts
  • Investigate the concept of center of mass in non-uniform mass distributions
  • Learn about the mathematical treatment of gravitational forces in finite versus infinite systems
USEFUL FOR

This discussion is beneficial for physicists, students of mechanics, and anyone interested in the complexities of gravitational interactions and the philosophical implications of Newtonian physics.

  • #511
Yes because the force on the center of mass will be equal to the sum of the forces on all particles in the system. Thus the forces add to be infinite. This is a problem.
 
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  • #512
First of all, the force to the mass center is NOT the sum of all forces. Not at all.

Do you know that?
 
  • #513
Tomaz Kristan said:
First of all, the force to the mass center is NOT the sum of all forces. Not at all.

Do you know that?
It hadn't occurred to us.

M\mathbf{R} = \sum_i m_i \mathbf{r}_i
M\dot{\mathbf{R}} = \sum_i m_i \dot{\mathbf{r}_i}
M\ddot{\mathbf{R}} = \sum_i m_i \ddot{\mathbf{r}_i}
 
  • #514
Do you know, that this is not the case?

You and I could be forced to accelerate in the opposite directions, yet the center of the mass of the you&me system, would not move at all. Let alone to be accelerated.

Just one example.
 
  • #515
This thread has gone long enough, and I believe that nothing has been achieved. This topic is now closed, and no new ones should be opened related to it.

Zz.
 

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