# Is it possible that the gravity that keeps our feet planted on the Earth is..

Discussion in 'Alternative Theories' started by jiveabillion, Jul 8, 2013.

1. ### billvonValued Senior Member

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Yes, that's wrong. Centrifugal force is based on mass, not density.

It is, actually.

Correct! Which is why:

2) why there is such a thing as a Clarke (geosynchronous) orbit

Centrifugal force has nothing to do with "push." It has to do with "pull." An object will continue in a straight line if unconstrained. If you do constrain it (i.e. tie a string to it) it will still want to go in a straight line - but the string will apply a force that pulls it away from that straight line.

Ideal Gas Law. Yes, without gravity the air around the planet would expand into space. (Indeed, would be thrown into space by the rotation of the Earth.)

Through tension. Strictly speaking there is no such thing as centrifugal force. What people perceive as centrifugal force is the tension in the "string" that is continually deflecting the object from its desired path.

In actuality if there was no gravity, the crust of the Earth would tend to continue to go in a straight line and go flying off into space, followed by most of the planet. The Earth has very little tensile strength.

There won't be.

Right, it provides a normal force only.

Centrifugal force does not propagate through you. It merely reduces your weight. This does not come about because anything is pushing on you; this comes about because your body wants to continue in the same direction.

3. ### jiveabillionRegistered Member

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Maybe density wasn't the right word for me to use. Lets say you were standing on a pile of sand. Wouldn't the individual grains of sand move more than your body with an equal amount of force pushing up them, making you "sink" further down into the pile?

How is it the same? If I were being spun around by rubber band, wouldn't the centripetal force increase as the rotation speed increased? It seems to me that it would be the opposite way with gravity.

But that only works if there is nothing in the way of an object's path around the planet.

I understand that, but what causes the force that can be felt? Is it not a collision (or pressure) of sorts? I know it's caused by the object's inertia and resistance to be constrained in a circular motion, but that has to propagate through the object somehow.

We are not talking about no gravity at the moment. We are talking about the Earth's movement and it's affect on gravity.

So Tension would be that collision (or pressure) that I mentioned above? Gravity doesn't do that though. It gets weaker at greater distances. Why would the tension increase?

Again, we aren't talking about no gravity right now. I think that was too radical of a concept to introduce while trying to find answers related to the Earth's movement.

??? So there is no centrifugal force on the Earth from its rotation around the Sun?

28,324.5kmh That's fast.
Here is a thought: Does the atmosphere actually move slower than the surface of the Earth?

If the Earth doesn't rotate fast enough to put me into an orbit around it's surface, then it must be pushing me. The inertial path that my body wishes to take due to gravity at that speed is not in an arc that would be large enough to clear curve of the Earth, it is much much less.

You've said that If I jump from the surface of the Earth, my velocity from the Earth's rotation would be tangent to the circle. But then gravity pulls me back down. Gravity does not pull me towards the point I jumped from, it just pulls me towards the center of the Earth. When I land, the surface of the Earth would have a greater velocity in the direction it is travelling relative to me, would it not? I would have a greater vertical velocity towards the center of due to the acceleration from gravity, but gravity does not accelerate me horizontally. Wouldn't my horizontal velocity relative to the surface of the Earth now be different? If so, wouldn't that cause additional force on my body from acceleration? If so, why would it be different if I didn't jump at all?

5. ### river

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You all realise that this thinking is out of date ....

7. ### jiveabillionRegistered Member

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No, I don't. I've never had a physics class, so I am learning all of this stuff right now.

Please direct me to all of the new ways of thinking.

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9. ### jiveabillionRegistered Member

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Would you care to summarize some of the more notable points that book makes?

10. ### river

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No not really

I'm just learning myself

But I did start a thread on " sub-quantum kinetics predictions " under alternative theories , go from there

11. ### jiveabillionRegistered Member

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I hope they are wrong. I really don't want a galactic superwave to obliterate all mammal life on Earth within the next few decades. If they are correct, then we really do need to find a really good way to store our history and knowledge for the future dominant race to discover.

12. ### river

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Sure

But the point is gravity is not how conventionally we all have been thinking upon gravity

Hence we are all well behind on the advanced thinking of gravity

We can though keep up with investigating Paul , and people like him

My quote is " I learn more from outside the mainstream than those that are in it , because the outside explain the mainstream , then explain their thinking , so I get both worlds explaination

13. ### jiveabillionRegistered Member

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I missed that part. Can you explain further?

14. ### river

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Gravity can have both attractive and repulsive forces

15. ### billvonValued Senior Member

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If the pile of sand weighs the same as you, then an equal force will result in an equal acceleration. ("Sinking" into sand, or water, or whatever, is a separate issue.)

Correct. That's one of the many reasons gravity and centrifugal forces are unrelated.

Tension.

It propagates via force, and that force is tension in the string. Tension in a larger centrifuge increases because the object's linear speed increases (assuming angular speed is the same.) Faster speed = more energy. More energy = harder to change direction. Harder to change direction = more force required.

Uh - OK. I'll switch to assuming you are talking about normal gravity.

There is. We call that force "tide." However (and this is important) if the Earth was a point gravity source there would be no tides and no centrifugal force. The reason there is centrifugal force on the far side of the Earth is that it is forced to orbit with the rest of the Earth but is 4000 miles farther from the Sun than the center. Thus it is not in a stable orbit; it wants to "go off on its own." Gravity prevents that, but the small amount of force that results gives rise to the tides.

This is something that is going to be hard to understand without basic physics.

It moves about the same speed. If it moves slower or faster we call that "wind."

Yes, that is called normal force.

Exactly. If the Earth did not push back, you would fall down (due to gravity) and very slightly forward (due to the speed of rotation.)

Yes, you do see a small difference if (for example) you jump off a platform. You don't go straight down, but go slightly in the direction of spin. This is called the Coriolis force. At human scales it is not measurable, but at larger scales (as in atmospheric or oceanic distances) it does cause some interesting effects, specifically winds and ocean currents.

16. ### river

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You are behind in the discussion

Gravity is both attractive and repulsive

Go back to my post #525 and investigate

17. ### billvonValued Senior Member

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But not chocolate? Why not chocolate? Free your mind!

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Exactly

19. ### flat universeRegistered Member

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It would not grow, if by grow you mean increase in volume. It would not decrease in density. If the earth was just made of water, gravity would still cause it to form a sphere. Its orbit around the sun would and does cause it to be slightly prolate or hot dog shaped with the long axis towards the sun. These are the tidal forces and the associated tides. The spin of the earth would cause and does cause the earth to change shape as well. The earth becomes oblate, hamburger-shaped, as it spins with the short axis being the axis of rotation. as it spins faster and faster it becomes more and more pancake shaped.

20. ### river

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While rotation has its merits

Gravity comes down to electrogravitics