How can we say there is Zero G force in space what about SUN's G ?

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Discussion Overview

The discussion revolves around the concept of gravitational force in space, particularly in relation to the Sun's gravity and the notion of "zero G" or microgravity experienced in orbit. Participants explore the implications of general relativity, the behavior of objects in gravitational fields, and the differences between gravitational and apparent weight.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the concept of zero G in space, suggesting that the Sun's gravitational force should still affect objects like a thrown rock.
  • Others explain that while there is microgravity in a spaceship orbiting Earth, gravity is still present in other frames of reference.
  • It is proposed that if a rock is thrown from a stationary position, it would fall towards the Sun, but if thrown from a moving object, it would maintain its orbital motion.
  • Some participants assert that planets are indeed falling towards the Sun but are moving sideways fast enough to remain in orbit.
  • There is a discussion about the range of gravitational force, with some suggesting it is limited while others argue it extends to infinity.
  • One participant expresses discomfort with Newton's equations, implying a potential issue with their interpretation.

Areas of Agreement / Disagreement

Participants express differing views on the nature of gravitational force in space, the implications of general relativity, and the distinction between gravitational force and apparent weight. There is no consensus on the range of gravitational force or the interpretation of gravitational effects on objects in motion.

Contextual Notes

Some statements reflect confusion regarding the relationship between gravitational force and motion, as well as the distinction between weight and apparent weight in different contexts. The discussion includes assumptions about the behavior of objects in gravitational fields that remain unresolved.

SBC
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How can we say there is Zero G force in space what about Sun's G (I mean in our solar system or above Earth )?

Ok.. General theory of relativity says about bending of space and time. If I throw a rock into space where there is no G force even the small rock should fall towards the Sun(what about Sun's G force it should pull the Rock? ). Does rock stays at same position or it will fall to words the sun according to General theory of relativity (due to bending of space and time )??

ok... planets revolve around sun (Why planets Revolve around sun why not fall towards sun?)... But the rock doesn't revolve and it should fall towards the sun ... ?

We say that Suns G force is far Grater that Earth and G force of suns range should be high !
Than why space shuttle and others don't fall towards the Sun ?

Than why on Earth Zero G force ?

How can G range be infinity ?

General theory of relativity says "Force is consequence of Geometry"

so G range is limited. Why infinite range?
 
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Welcome to PF!

Hi SBC! Welcome to PF! :smile:
SBC said:
»How can we say there is Zero G force in space what about Sun's G (I mean in our solar system or above Earth )?

We don't, we say there is microgravity in space … in a spaceship orbiting the Earth (with its engines off), a book floats because it too is in orbit, and its orbital speed is almost exactly the same as that of the spaceship (exactly exactly only if it is at the same distance from Earth as the centre of mass of the spaceship).

Using the spaceship as a frame of reference, there is almost zero gravity.

But in any other frame, there is plenty of gravity, as you say! :smile:
Ok.. General theory of relativity says about bending of space and time. If I throw a rock into space where there is no G force even the small rock should fall towards the Sun(what about Sun's G force it should pull the Rock? ). Does rock stays at same position or it will fall to words the sun according to General theory of relativity (due to bending of space and time )??

ok... planets revolve around sun (Why planets Revolve around sun why not fall towards sun?)... But the rock doesn't revolve and it should fall towards the sun ... ?

If you could place the rock stationary, then yes it would fall towards the Sun.

But if you threw it from Earth, or from a spaceship orbiting the Sun, it would start with all the orbital energy of the Earth or the spaceship, and it would continue to orbit the Sun near the Earth or the spaceship.

The planets do fall towards the Sun, but they are moving sideways so fast that manage to stay in orbit …

This is what Sir Isaac Newton realized when he saw the apple fall … if you throw an apple fast enough sideways, it will still fall, but the sideways movement keeps it in orbit. :wink:
We say that Suns G force is far Grater that Earth and G force of suns range should be high !
Than why space shuttle and others don't fall towards the Sun ?

Because the space shuttle orbits the Sun at the same speed as the Earth does.
 
Last edited:


tiny-tim said:
Hi SBC! Welcome to PF! :smile:


We don't, we say there is microgravity in space … in a spaceship orbiting the Earth (with its engines off), a book floats because it too is in orbit, and its orbital speed is almost exactly the same as that of the spaceship (exactly exactly only if it is at the same distance from Earth as the centre of mass of the spaceship).

Using the spaceship as a frame of reference, there is almost zero gravity.

But in any other frame, there is plenty of gravity, as you say! :smile:


If you could place the rock stationary, then yes it would fall towards the Sun.

But if you threw it from Earth, or from a spaceship orbiting the Sun, it would start with all the orbital energy of the Earth or the spaceship, and it would continue to orbit the Sun near the Earth or the spaceship.

The planets do fall towards the Sun, but they are moving sideways so fast that manage to stay in orbit …

This is what Sir Isaac Newton realized when he saw the apple fall … if you throw an apple fast enough sideways, it will still fall, but the sideways movement keeps it in orbit. :wink:


Because the space shuttle orbits the Sun at the same speed as the Earth does.

I like your reply but if planets are not falling towards sun why not stone ?

How can G range be infinity ?
 
SBC said:
I like your reply but if planets are not falling towards sun why not stone ?

Because if the stone is launched from a planet, it will have the velocity of the planet in addition to its launch velocity.
How can G range be infinity ?

I don't understand why you're asking this …

why wouldn't it extend to infinity? why should it stop somewhere? :confused:
 
General theory of relativity says "Force is consequence of Geometry"
so G range is limited.

GTR says there is no force, only geometry of space-time, which extends everywhere.
 


SBC said:
I like your reply but if planets are not falling towards sun why not stone ?

How can G range be infinity ?
The planets *are* falling towards the Sun. However, their tangential velocities coupled with that inward acceleration makes them orbit the Sun rather than fall straight into it.

In your original post, you are confusing weight (gravitational force) with apparent weight (everything but gravitational force). We call space a zero-g environment because an astronaut's apparent weight is nearly zero on orbit. An astronaut's actual weight is about 90% that of that on the ground.
 
tiny-tim said:
Because if the stone is launched from a planet, it will have the velocity of the planet in addition to its launch velocity.I don't understand why you're asking this …

why wouldn't it extend to infinity? why should it stop somewhere? :confused:

If you are of my age hey BRO !
if you are older than me sir,

2zh01s3.jpg


look at this .. I don't know why I feel that I found something wrong with sir.isaac Newton's Equation.
 
I think what you've found is a personal discomfort, nothing more.
 
ok... planets revolve around sun (Why planets Revolve around sun why not fall towards sun?)... But the rock doesn't revolve and it should fall towards the sun ... ?


------------->it (earth) will fall toward the sun but that's a long time from now


:wink:
 
  • #10
obing said:
------------->it (earth) will fall toward the sun but that's a long time from now


:wink:

No … the Sun will come to meet us! :wink:

We're so lucky! :-p
 

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