Gravitational force of a neutron star

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Discussion Overview

The discussion revolves around the gravitational force of neutron stars, particularly focusing on how gravitational attraction changes when a star collapses into a neutron star. Participants explore the relationship between mass, density, volume, and gravitational force, considering both theoretical and conceptual aspects of gravity in astrophysical contexts.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that a neutron star, despite having the same total mass as the original star, exhibits greater gravitational attraction due to its increased density and reduced radius.
  • Others argue that gravitational attraction is influenced by the distance to the center of mass, asserting that being closer to the center of a neutron star results in stronger gravitational effects.
  • A later reply questions the assumption that total mass alone determines gravitational attraction, suggesting that the radius and density also play critical roles.
  • Some participants emphasize the importance of Newton's formula for gravitational force, which states that gravitational force is proportional to mass divided by the square of the radius.
  • There is a discussion about the implications of shedding mass versus collapsing into a neutron star, with some participants speculating on how these scenarios affect gravitational attraction.
  • One participant seeks to understand why the center of gravity is significant in determining gravitational force, rather than just the total mass beneath a person standing on a star.

Areas of Agreement / Disagreement

Participants express differing views on the factors that determine gravitational attraction, with no consensus reached. Some emphasize mass and density, while others highlight the importance of radius and distance to the center of mass.

Contextual Notes

Participants reference Newton's formula and discuss various scenarios involving mass and density, but there are unresolved assumptions regarding how these factors interact in different astrophysical contexts.

  • #31
Maybe I can make an analogy on the topic. Newtons formula speaks for itself, but to put it into another picture.

Imagine you are on the surface of the sun with mass 1 sun. The suns radius is about 700,000 km. You have the whole mass of the Sun pulling on you. Since gravity gets weaker with distance, you have half the mass of the Sun pulling on you from within that 700,000 km radius and the other half pulling on you from up to 1.4 million km away.
Now shrink that mass to about a couple of km. Now you have the whole Suns mass pulling on you from within a couple of km. Your more closer to it all!, so it is stronger.
 
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  • #32
JohnnyGui said:
Thank you, I think I'm now at the root of my problem here. Is it possible to answer why exactly the center of gravity determines the force instead of the total amount of mass beneath you without saying that it's just the way how nature works? I think I'm trying to understand the roots of how gravity works here.

It was all worked out by Isaac Newton in the 17th century. Europe was most impressed. The idea is that you sum up the gravitational attraction of every tiny piece of each body. The result is surprisingly simple.
 

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