Accelerating away from a mass mitigates gravity's pull on the accelerating object. Would the same be true for an object accelerating towards the center of the mass?


No. It's not exactly the same.

When you're accelerating away from the massive object, the gravitational pull decreases - yes. But, you'll be under the influence of the field at whatever distance other than $\infty$. But in case of center of mass (assuming there's no other source nearby), you'll be pulled equally in all the directions (floating) which make you feel that you aren't affected by gravity. This is a different case. Because, you can be stretched into pieces if you're inside a sufficiently massive object.

So, it's better to pronounce this center of mass comically as a position of gravity balancing equilibrium..!

  • $\begingroup$ Crazy, I thought gravity would just continue to push on you from every direction at the core of a massive object. Are you saying that it is actually a matter of being pulled away from the center? That is fascinating. I had never thought of it that way. $\endgroup$ – Argo Apr 9 '13 at 21:47
  • $\begingroup$ @Zach: Classically, Gravity is an attractive force always. I didn't say that matter is pulled away from the center of mass. Objects are formed by their gravitational collapse based on density fluctuations. If the density of your body differs extremely from the massive object, which I meant at the last, then there's a large probability that you'll be pulled in all directions (because you're at the center) and finally BOOM..! ;-) $\endgroup$ – Waffle's Crazy Peanut Apr 10 '13 at 1:39
  • $\begingroup$ Yes...it took me a bit but I think I see what you are saying. Assuming you are not crushed to smithereens by everything on top of you as you journey to the center, you are saying that you would be pulled by the stronger gravity that is OUTSIDE of you, due to density differences. Yes? That is amazing. I am loving this. $\endgroup$ – Argo Apr 10 '13 at 19:56

I'm not sure what you mean by:

Accelerating away from a mass mitigates gravity's pull on the accelerating object

because accelerating away from a mass increases the force you feel i.e. it make gravity feel stronger not weaker. You can do the experiment by going into an elevator. As it accelerates upwards and away from the centre of mass of the Earth you briefly feel heavier. As it accelerates downwards and towards the centre of the Earth you feel lighter.

I wonder if you meant that the gravitational field gets weaker as you move away from a heavy object ...

Response to comment

You say in the comment:

With enough speed you will escape the pull of gravity

and this is certainly true, and that speed is called the escape velocity. However this isn't accelerating because you're presumably thinking of the object being accelerated up to some velocity then left to move freely. The interesting thing is that if you're moving freely i.e. if you're not burning your rockets and nothing else is pushing you, then you will feel no gravity at all. It doesn't matter whether you're headed outwards, so gravity is slowing you, or headed inwards so gravity is accelerating you. In both cases you will feel no gravity.

  • $\begingroup$ +1: I have a bad feeling about the question now..! ;-) $\endgroup$ – Waffle's Crazy Peanut Apr 9 '13 at 16:15
  • $\begingroup$ Crazy, LOL. What do you mean? $\endgroup$ – Argo Apr 9 '13 at 18:17
  • $\begingroup$ Oh...I see. :-) $\endgroup$ – Argo Apr 9 '13 at 18:17
  • $\begingroup$ John, yes. With enough speed you will escape the pull of gravity I am assuming. I think what I mean by the queetion is, when accelerating from say orbit downward, is it possible to that the feeling of "gravity" is coming from the opposite direction, pulling from above rather than below? The gravity from the acceleration downward is felt more strongly than the pull from the planet? $\endgroup$ – Argo Apr 9 '13 at 18:26
  • $\begingroup$ @Zach: I've edited my answer to respond to your comment. $\endgroup$ – John Rennie Apr 9 '13 at 18:57

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