All Questions
Tagged with gravity reference-frames
103
questions
-1
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3
answers
101
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Can two particles ever be in equilibrium under their mutual gravitational forces alone?
Can two particles be in equilibrium under the influence of their mutual gravitational forces alone?
Obviously, if the two particles are kept at rest at a distance apart, one will exert an attractive ...
- 25.3k
8
votes
5
answers
1k
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Do you always experience the gravitational influence of other mass as you see them in your frame?
You see a galaxy far away. That galaxy is attracting you with a certain amount of gravity. I'm wondering if the gravity influence of the galaxy on you, as measured by you, always ends up being what ...
- 1,148
3
votes
2
answers
86
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Tug of war between observers in frames with different rate of time
You have a very dense hollow sphere of matter. Observer A is inside the sphere inside a rocket. Observer B is in an identical rocket outside the sphere where the ring's gravity is negligible. They are ...
- 15.9k
3
votes
2
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85
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How is it that energy of matter yields gravity if the amount of energy in a system is frame dependent while the force caused by gravity is not?
I've been told that the gravitational field arises due to the energy density terms in the stress-energy tensor of matter and therefore that all energy of matter exerts a gravitational field effect, ...
- 9,611
4
votes
5
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262
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How is Gravity, assuming only General Relativity, *not* like Centrifugal Force?
It is common to state that "Gravity is not a force" due to its interpretation as a curvature effect in general relativity. By this, is it right to say that gravity is a fictitious force due ...
- 3,138
25
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4
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If gravity is not a force, then how come gravitational assists work?
I have learned about general relativity and how gravity arises from spacetime curvature. And I have always been taught that gravity is not a real force in the sense that
$$\frac{dp}{dt} = 0$$
And from ...
- 1
0
votes
0
answers
28
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When we are on the ground do we still accelerate with 9.8 m/s²? [duplicate]
Do we accelerate with 9.8 m/s² when we are on the ground , if so why we do not fall inside the eart . How is the net force is zero , how many real forces acts on the body ?
- 207k
1
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27
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Fictitious forces and the Unruh effect
Here is a (practically infeasible) method to determine whether you are in a non-inertial frame of reference:
Look around you, and calculate all of the forces acting on you. The piece of lint on the ...
- 179
0
votes
2
answers
330
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Earth as inertial reference frame: finite radius effects
In a recent question I tried to clarify under what conditions the Earth can be considered as an inertial reference frame. The opinions, summarized in my own answer to the cited question, are that
...
- 2,402
-2
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1
answer
139
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If time moves slower the faster you go. Doesn't that mean that the gravity experienced will be lower too?
Disclaimer: I still don't understand the theory of general relativity. I'm completely ignorant.
I was watching the movie Interstellar yesterday and saw their interpretation of time dilation, I also ...
- 6,217
3
votes
1
answer
117
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Transformation of derivatives of coordinates
I am quite new to this topic. Please bear with me.
Suppose we are given a transformation of both time and space coordinate's derivatives as
$$
\partial_t\to D_t=\partial_t-f(t,x)\partial_t\\
\nabla\to ...
- 1,713
2
votes
1
answer
164
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When we spin and feel our arms fly, is it the effect of gravity?
If accelerating reference frames can be treated as normal inertial reference frames but with gravity, then for a rotating reference frame, is the centrifugal $force = gravity$ ?
More specifically, I ...
- 411
2
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2
answers
2k
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What kind of coordinate change is needed to make gravity disappear?
I understand that the Christoffel symbols associated with the metric will vanish locally once you perform the appropiate change of coordinates. These new coordinates correspond to an observer in free-...
- 16.7k
4
votes
2
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371
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Are objects in an uniform field inertial?
It is currently understood that gravity is not actually a force, and a fact that is often used to show this is that an object in free fall doesn't "feel" that it is accelerating and is thus ...
- 10.7k
2
votes
2
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In the context of the equivalence principle, is gravity a fictitious force?
I am currently self studying general relativity and I have a question regarding the equivalence principle:
If an observer is in an elevator in deep space (or Minkowski space) where there is no ...
- 2,327