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Flat Earth Theory / Re: Spirit Levels on a Flat Earth
« on: September 18, 2019, 04:06:21 PM »The question is why is there no difference?.
Because gravity is a force acting downwards. By "downwards" I mean relative to your position, assuming you are standing up.
It's actually towards the centre of mass of the earth and on a globe earth downwards is relative to your position, but to all intents and purposes gravity acts downwards.
Were the earth flat, there was no gravity and it was UA creating the force we call gravity then that force would act downwards and be equivalent.
The headline is both produce a force which acts in a downwards direction relative to your position.
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The reason the bubble moves from off center and lands center when you move it is because when you move the level you are adjusting or "realigning" how the force of gravity is acting on the vial. The force of gravity on the vial has changed. How gravity is effecting the vial is different because its location is different.
Well, there would be a very slight difference because one end is higher than the other but that difference is so trivial that it's not what causes the bubble to move. Pete has done the maths for you.
The real difference is that the spirit level is no longer parallel to the ground so the force of gravity is no longer perpendicular to the tube - again, see my diagrams.
You have changed the orientation of the tube, the level of the liquid is still parallel to the ground because of the downward force of gravity but because the tube is not level the bubble is now off centre because the top of the tube is not at the centre.
This is true whether the force is caused by gravity or UA.
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Sorry to keep repeating, but it is the central point to the issue and everybody just seems to ignore it.
No-one is ignoring you but Pete actually does have a good grasp of physics - better than me, I think. And he is right here.
It's not the changed force of gravity, it's the changed orientation of the tube. The force acting downwards remains constant whatever is causing the force.