Our Weight

originally posted by: suicideeddie
a reply to: Nochzwei

as i see it.if you include your mass as part of the earths (as a static system)and introduce frame dragging and related proposals the anwser could be yes, the result could be measurable at a quantum level.

You don't need frame dragging and quantum measurements. It's simply a case of centripetal forces, which could be calculated on a macro level using Newtonian physics.

shhosh dont tell him that, i wanted him to start googling and learn something

originally posted by: TerryDon79

originally posted by: Nochzwei

originally posted by: TerryDon79

originally posted by: Nochzwei

originally posted by: DenyObfuscation
a reply to: Nochzwei
With the string being about 93 million miles long and the ball taking a year to make one revolution, how much force are we even talking about? At any given moment the deviation from a straight path would seem to me to be almost negligible.

All orbiting bodies travel in a straight line

Excuse me?!

If something is ORBITING it certainly doesn't travel in a straight line.

Yes they do

Do you know the difference between a straight line and a circle?

| - straight line
O - circle

If everything that orbits is going in a straight line then all the planets would have to be in exactly the same place, all the time with no deviation.

Yes they are travelling in a straight line while falling

a reply to: Nochzwei

What do you mean by falling vertically, vertically in relation to what? I don't get the question.

originally posted by: Nochzwei
We know that earth and us on it, free falls vertically around the sun. So our inertia acts vertically upwards. Now take a hypothetical situation, where earth is not falling around anything, so there will be no inertia acting vertically upwards. In such a situation, wont our weight be greater than what it presently is?

No. As explained below, in a circular orbit in Newtonian mechanics, which is sufficient to answer this question, centripetal and centrifugal forces are equal and opposite, so they don't affect your weight. So your question is, what happens if I remove both those forces that cancel each other out? There's no significant change in your weight. It would be the same as if you were holding the middle of a rope used in a "tug-of-war" where both sides were pulling equally, and then both sides suddenly dropped their ropes and stopped pulling. What effect would that have?

There's a slight change in your weight if you go from the equator to the north pole due your inertia from the Earth's rotation, but that's different because you're not in orbit.

originally posted by: ErosA433
Centripetal force is an example of a pseudo-force.

Yes in the gravity context of this thread, Einstein would probably say that, but Newton thought it was real and in a larger context like spinning a ball on a string centripetal force can be real. Centrifugal force is always a pseudo force though in every context I can think of, and I think even Newton would have agreed to that. As others have said it's really inertia.

originally posted by: wildespace
a reply to: Nochzwei

When you're falling downwards, you don't have inertia acting upwards. For moving bodies, inertia acts in the direction of travel.

This may be semantics, but yes inertia acts in the direction of travel. However since the direction of travel from the reference frame of an orbit can be viewed as having an "upward" component then yes, not only does inertia act partially "upwards", but in a circular orbit (and the Earth's orbit isn't far from circular), the "upward" or maybe "outward" component of inertia exactly balances the centripetal force due to gravity using Newtonian mechanics. Not quite exactly in the case of the Earth orbiting the sun, but pretty close. The Earth's orbit is slightly elliptical and is moving slowly away from the sun because of tidal interaction.

Here's a diagram showing what I'm talking about. These "ramps" are created by the tendency of inertia to move the object "upwards" or "outwards":
www.nhn.ou.edu...


In this model, each one of these "ramps" shows the motion "upward" or outward. In circular motion where the ramps are made infinitely small I suppose you could say those ramps have disappeared but the effect is still there.

originally posted by: Soylent Green Is People
Nochzwei is probably talking about the fact that orbiting objects move in a straight line through space-time

I doubt it, you're apparently not aware of the fact that Nochzwei is more of an anti-relativity guy than a relativity guy, which is why these threads belong in skunk works and not the science forum. He doesn't want to discuss science, more like anti-science, mainstream is wrong, all the experiments proving relativity are wrong, no scientists have any idea what they are doing, Nochzwei is the only one with a clue what's really going on, according to him.

originally posted by: Arbitrageur
I doubt it, you're apparently not aware of the fact that Nochzwei is more of an anti-relativity guy than a relativity guy, which is why these threads belong in skunk works and not the science forum. He doesn't want to discuss science, more like anti-science, mainstream is wrong, all the experiments proving relativity are wrong, no scientists have any idea what they are doing, Nochzwei is the only one with a clue what's really going on, according to him.

After nearly 250 pages of your "Ask any question you want about Physics" thread, I lost my playbill and no longer know who all of the players are.

originally posted by: Arbitrageur
centripetal and centrifugal forces are equal and opposite, so they don't affect your weight.

What then causes the kinds on the playground's merry-go-round to fly off away from the center?

So your question is, what happens if I remove both those forces [centripetal & centrifugal] that cancel each other out?

I thought the question was, what would happen if we removed gravity, or more specifically, does centrifugal force counter gravity?

There's a slight change in your weight if you go from the equator to the north pole due your inertia from the Earth's rotation

I agree and I think that this is the crux of the OP’s question.

originally posted by: ErosA433
Centripetal force is an example of a pseudo-force.

originally posted by: Arbitrageur
Yes in the gravity context of this thread, Einstein would probably say that, but Newton thought it was real and in a larger context like spinning a ball on a string centripetal force can be real

I would agree with Newton. Centripetal force (center seeking) is a real force. It is angular acceleration towards the center similar to making a right hand turn in your car. How we know it is a real force is based on the effects of inertia, the resistance to acceleration. Centrifugal force, as you pointed out, is the fictitious or pseudo force. BTW gravity is also considered a fictitious force.

originally posted by: wildespace
When you're falling downwards, you don't have inertia acting upwards. For moving bodies, inertia acts in the direction of travel.

originally posted by: Arbitrageur
This may be semantics, but yes inertia acts in the direction of travel

I find this confusing. When you’re falling to Earth, gravitational acceleration, you do not experience inertia. I assume this is the reason gravity is considered a fictitious force. How does inertia act in the direction of travel? Do you mean inertia is acting in the direction of Earth’s orbit around the Sun, straight line as opposed to a curve? If I didn't know better I would think there is some confusion between inertia and momentum.

I doubt it, you're apparently not aware of the fact that Nochzwei is more of an anti-relativity guy…
Nochzwei is the only one with a clue what's really going on, according to him.

Oooh, I want to have a clue too.

Nochzwei, perhaps you would enjoy reading this site; Relativity The Special and General Theory
It is the most comprehensive literature on relativity that I have found. It is a translation of Einstein’s own work. He was more of a “lay person” thinker in my opinion.

originally posted by: DenyObfuscation
With the string being about 93 million miles long and the ball taking a year to make one revolution, how much force are we even talking about? At any given moment the deviation from a straight path would seem to me to be almost negligible.

The force is great enough to keep the Earth from falling into the Sun, I would think that is far from negligible. As far as the force acting on a single person then the amount would seem negligible.

originally posted by: Nochzwei
All orbiting bodies travel in a straight line

This concept is oversimplified to the point of being incorrect. Due to the effects of gravity, which is ubiquitous, everything travels in some sort of curve. Travel in a straight line in any direction long enough and you’ll find your trajectory will be altered at some point into a curve; hyperbolic, parabolic or elliptical.

ADD; The best you could do is constantly change your course to attempt to achieve a straight line but since everything is in motion what would be your frame of reference? You might see a straight line trajectory yet from another frame of reference it is curved, relatively speaking.

originally posted by: Devino
What then causes the kinds on the playground's merry-go-round to fly off away from the center?

I thought the question was, what would happen if we removed gravity, or more specifically, does centrifugal force counter gravity?

They typically don't let go but if they do they follow the motion of one of the ramps in my diagram except there's nothing to bring them back toward the center, so they usually stop after a short distance from friction. But in the more realistic case where they hang on and keep going in a circle, it's like an orbit and the two "forces" are exactly balanced.

The question wasn't about removing gravity because if that happened there would be no weight, only mass. No the question in the OP isn't entirely hypothetical because in simulations of solar system formation some of the early planets formed get flung out of the solar system and become rogue planets, so this happens with gravity and there is still gravity and is more or less what the OP described:

"Now take a hypothetical situation, where earth is not falling around anything, so there will be no inertia acting vertically upwards."

I agree and I think that this is the crux of the OP’s question.

You agree or you disagree because in your next comment you disagree:

I find this confusing. When you’re falling to Earth, gravitational acceleration, you do not experience inertia.

You just agreed with me that you weigh less at the equator than at the pole due to inertia. Make up your mind, do you or don't you?

Also standing on the ground has different dynamics than being in orbit so keep that in mind when comparing Earth's rotation to the Earth's orbit around the sun. The main difference is there's no ground to hold you up in orbit so the forces must be equal and opposite for a circular orbit. Your weight can vary on the ground and no they are not the same question and you're raising a different point than the OP.

originally posted by: Arbitrageur
The question wasn't about removing gravity

The question seems to be whether or not centrifugal force counters gravity and my answer is that it does. Perhaps the OP could clarify.

You agree or you disagree because in your next comment you disagree:…
You just agreed with me that you weigh less at the equator than at the pole due to inertia. Make up your mind, do you or don't you?

You stated two different scenarios. I agreed with one and asked for clarification on the other. How much would you weigh and how much inertia would you feel during freefall?

originally posted by: Devino
The question seems to be whether or not centrifugal force counters gravity and my answer is that it does. Perhaps the OP could clarify.

If the Earth isn't going around anything there's no centrifugal or centripetal forces. If the earth is going around the sun there are both but they sum to zero so there's no difference in your weight. So yes you have centrifugal and centripetal forces in orbit but they're the same in a circular orbit and sum to zero so when you add zero to your weight how much of a change is that?

You agree or you disagree because in your next comment you disagree:…
You stated two different scenarios. I agreed with one and asked for clarification on the other. How much would you weigh and how much inertia would you feel during freefall?

I never stated a freefall scenario. We're all falling toward the Earth right now but it's not freefall because the ground stopped us from falling any further.

If you freefall in Earth's atmosphere you feel the atmosphere but in space you wouldn't feel the atmosphere or gravity you'd feel weightless, like the astronauts. I don't know what you mean by "feel inertia", the astronauts only feel "zero-G" in the ISS. If they weren't orbiting the Earth but falling straight down they'd still feel zero-G. Two different inertia trajectories, no change in feeling initially. They'd feel hot in the second case when they entered the atmosphere but I wouldn't call that feeling inertia, more like feeling vaporization.

originally posted by: Jonjonj
a reply to: Nochzwei

What do you mean by falling vertically, vertically in relation to what? I don't get the question.

Falling vertically towards the centre of the sun

originally posted by: Nochzwei

originally posted by: Jonjonj
a reply to: Nochzwei

What do you mean by falling vertically, vertically in relation to what? I don't get the question.

Falling vertically towards the centre of the sun

How would you define it as vertically? Could be horizontally or at another angle. Would all depend on what you would reference as up and down.

originally posted by: TerryDon79

originally posted by: Nochzwei

originally posted by: Jonjonj
a reply to: Nochzwei

What do you mean by falling vertically, vertically in relation to what? I don't get the question.

Falling vertically towards the centre of the sun

How would you define it as vertically? Could be horizontally or at another angle. Would all depend on what you would reference as up and down.

Orbiting bodies always fall vertically towards the central object

but, we're travelling in a stretched spiral as the sun hauls azz ...I think stretched pretty good. Towards Spica the flashing star.....and riding a spoke of stars..... also riding.......the milky way in a straight line?

About gravity....in an electric universe, could gravity be the inductance resultant from our motions in those sectors.......he. ....he

originally posted by: Arbitrageur
If the Earth isn't going around anything there's no centrifugal or centripetal forces. If the earth is going around the sun there are both but they sum to zero so there's no difference in your weight.

I see your point. The Earth’s centrifugal force is countered by the Sun’s gravity and it shouldn’t be any different for us standing on the surface. I was also considering the Earth’s rotation yet that isn’t the OP’s question. I think that is where I got confused.

I never stated a freefall scenario.

Then I don’t believe I was disagreeing with you.

I feel as though I jumped into the middle of a debate that started in another thread.

OMG there is so much wrong in this thread, it is not even funny.

The motion of bodies (in an isolated system) is governed by the conservation of momentum, angular momentum and energy.

An object will maintain its momentum until a force acts upon it. A force is per definition the change of momentum. There is no need for any inertial force nonsense.


Einstein went a step further and got rid of gravitational forces by replacing them with a curved spacetime. But I'd recommend to get a firm grasp of classic physics of motion before looking into GR.

You are right about conservation of momentum, but know ye not einstein' Gr is all bunk.
a reply to: moebius

For Orbiting bodies there is no centrifugal or centripetal force

a reply to: Nochzwei
If you don't believe in General Relativity, and there's no centripetal force, what's holding the Earth in orbit around the sun?

When others have said the centripetal force is fictitious they were saying that because of general relativity, so if you don't believe GR I don't see how you can deny centripetal force and still keep the Earth in orbit.