Seafloor Spreading??

There isn't one (see below).

How can acceleration occur without a force causing it? a = F/m

One is pulling you down, the other is keeping you up.

You just repeated the question, not the answer. What is the difference between pulling down and pushing up? All frames of reference are equal.

Only when you are in contact with the Earth, directly or otherwise.

If that were the case, It would follow that once I am in the air, no change of momentum occurs. But it does. So this is false. I repeat: a = F/m.

That response was not to you, but to a separate question asked by another user.

So your opinions change depending on who you are answering to? Is the ground accelerating or is it not?

How can acceleration occur without a force causing it? a = F/m

Exactly!  Now we are getting somewhere.

You just repeated the question, not the answer. What is the difference between pulling down and pushing up? All frames of reference are equal.

Only inertial frames are equal.  Non inertial frames invoke fictitious forces.  Do you see where this is going?

If that were the case, It would follow that once I am in the air, no change of momentum occurs. But it does. So this is false. I repeat: a = F/m.

Ok.  Let's do another experiment to see who is right:

Get an accelerometer app for your phone.  Hold it in your hand and jump off of something.  What does the accelerometer read?  If it reads zero, I am right.  If it reads 9.8m/s^2, then you are right.  Let me know what you find out.

So your opinions change depending on who you are answering to?

No, the person was asking a FE specific question.  The answer was FE specific.  We, however, were not discussing FE/RE.  We are discussing how gravity is fake.

Is the ground accelerating or is it not?

Well, technically, yes. At roughly 9.8m/s^2.

Hey, TheEngineer, do you finally know what the difference between gravity and the force of gravity is?

Also, can you tell me the definition of acceleration?

I am still waiting for the day you can answer these questions correctly.

Sure:

Gravity is a word.

The force of gravity is a fictitious force that arises from the transformation of a non inertial frame of reference into an inertial one.


1. Coordinate acceleration is the rate of change of velocity.
2. Physical acceleration is the acceleration of a body relative to an inertial condition.

What do I win?  More opportunities to make you look foolish I hope.  Because that's what I do to you and Discount Chemist when you guys try to play these games.  It never ends well for you two.

Sure:

Gravity is a word.

The force of gravity is a fictitious force that arises from the transformation of a non inertial frame of reference into an inertial one.


1. Coordinate acceleration is the rate of change of velocity.
2. Physical acceleration is the acceleration of a body relative to an inertial condition.

What do I win?  More opportunities to make you look foolish I hope.  Because that's what I do to you and Discount Chemist when you guys try to play these games.  It never ends well for you two.

You answered wrong on one question. Let me rephrase my question:
Hey, TheEngineer, do you finally know what the difference between the definitions of gravity and the force of gravity is? And please answer in as simple terms as possible (so try using everyday words if possible, because that is all we need).

Also, you missed the most basic and pure definition of acceleration. Can you please give me this definition?

I answered your questions correctly.  Why don't you just tell me the answers you want so we can all laugh at you?

I answered your questions correctly.  Why don't you just tell me the answers you want so we can all laugh at you?

You missed the definition for gravity. Well, whatever.

Gravity is the phenomenon which causes acceleration between bodies with mass.

The force of gravity is weight.

The pure definition of acceleration is a=dv/dt. Surprised you didn't know this.

Only inertial frames are equal.  Non inertial frames invoke fictitious forces.  Do you see where this is going?

Yes. You want to equate saying "there is no force" with saying "the force is fictious". But if the frame of reference is under acceleration, a force must be acting on it. Hence there is a force.

Ok.  Let's do another experiment to see who is right:

Get an accelerometer app for your phone.  Hold it in your hand and jump off of something.  What does the accelerometer read?  If it reads zero, I am right.  If it reads 9.8m/s^2, then you are right.  Let me know what you find out.

Ok, the result is as you describe it. Now what does that mean?

No, the person was asking a FE specific question.  The answer was FE specific.  We, however, were not discussing FE/RE.  We are discussing how gravity is fake.

A pseudo-force is fake? That doesn't strike you as a tad dishonest?

Well, technically, yes. At roughly 9.8m/s^2.

So, technically, a force is accelerating the ground?

Quote from: TheEngineer on January 28, 2016, 10:13:05 PM

Only inertial frames are equal.  Non inertial frames invoke fictitious forces.  Do you see where this is going?

Yes. You want to equate saying "there is no force" with saying "the force is fictious". But if the frame of reference is under acceleration, a force must be acting in it. Hence there is a force.

Quote from: TheEngineer on January 28, 2016, 10:13:05 PM

Ok.  Let's do another experiment to see who is right:

Get an accelerometer app for your phone.  Hold it in your hand and jump off of something.  What does the accelerometer read?  If it reads zero, I am right.  If it reads 9.8m/s^2, then you are right.  Let me know what you find out.

Quote from: TheEngineer on January 28, 2016, 10:13:05 PM

No, the person was asking a FE specific question.  The answer was FE specific.  We, however, were not discussing FE/RE.  We are discussing how gravity is fake.

A pseudo-force is fake? That doesn't strike you as a tad dishonest?

Quote from: TheEngineer on January 28, 2016, 10:13:05 PM

Well, technically, yes. At roughly 9.8m/s^2.

So, technically, a force is accelerating the ground?

TheEngineer is right. Gravity is not a force, so when you are i free fall in a vacuum and accelerating towards a body with a mass, you are not subjected to any forces. When you are standing on the ground, the ground is accelerating you upwards at 9.82m/s. And the ground below the ground is accelerating that ground up at 9.82m/s. This models gravity as bent space-time. Because space-time is bent, you are actually moving with constant velocity (during frictionless free-fall) but you appear to be accelerating. However, gravity is also a force, but not as described by newtonian mechanics, but as described by the standard modell. This assuming that the graviton is real. Because it is modelled as bent space-time, it is really hard to understand the geometry (4 dimensions).

If I jump off something the accellerometer reads 9.8.

TheEngineer is right. Gravity is not a force, so when you are i free fall in a vacuum and accelerating towards a body with a mass, you are not subjected to any forces. When you are standing on the ground, the ground is accelerating you upwards at 9.82m/s. And the ground below the ground is accelerating that ground up at 9.82m/s. This models gravity as bent space-time. Because space-time is bent, you are actually moving with constant velocity (during frictionless free-fall) but you appear to be accelerating. However, gravity is also a force, but not as described by newtonian mechanics, but as described by the standard modell. This assuming that the graviton is real. Because it is modelled as bent space-time, it is really hard to understand the geometry (4 dimensions).

So gravity is a force, but gravity is not a force. I appear to be accelerating but I appear to not be accelerating.

I appreciate the effort to explain, but I don't quite get how this is supposed to work. How can a theory based on empirical observation state that there appears to be a force but there is not actually a force? That sounds like metaphysics. Explaining a force as the result of bent space-time isn't the same as saying there isn't a force at all.

Wow.  I guess you are really out of touch.  No wonder you don't understand what I am saying.

Ahh...you like games of semantics. Redefined, not proven incorrect. If you think that the way gravity is described in general relativity backs up an accelerating flat earth, i have a really hard time seeing how you come to that conclusion. Does flat earth bend spacetime? If it does, well, it has gravity. If not, why not? See, the problem is still there.

F=ma

That a is for acceleration.  If acceleration is zero, then the force is zero.  So if your scale reads something positive, then you are accelerating.  Something you guys said was incorrect.  So what is it?

You dont understand that the acceleration of flat earth that FE rests upon is something completely different from acceleration due to curvature of spacetime? Sounds like you think they are the same thing.

Btw, f=a/m means that if an object is not accelerating, there is no net force acting on it, not that no forces act on it. Dont know how you got that idea.

Quote from: Master_Evar on January 29, 2016, 12:02:18 AM

TheEngineer is right. Gravity is not a force, so when you are i free fall in a vacuum and accelerating towards a body with a mass, you are not subjected to any forces. When you are standing on the ground, the ground is accelerating you upwards at 9.82m/s^2. And the ground below the ground is accelerating that ground up at 9.82m/s. This models gravity as bent space-time. Because space-time is bent, you are actually moving with constant velocity (during frictionless free-fall) but you appear to be accelerating. However, gravity is also a force, but not as described by newtonian mechanics, but as described by the standard modell. This assuming that the graviton is real. Because it is modelled as bent space-time, it is really hard to understand the geometry (4 dimensions).

So gravity is a force, but gravity is not a force. I appear to be accelerating but I appear to not be accelerating.

I appreciate the effort to explain, but I don't quite get how this is supposed to work. How can a theory based on empirical observation state that there appears to be a force but there is not actually a force? That sounds like metaphysics. Explaining a force as the result of bent space-time isn't the same as saying there isn't a force at all.

You didn't read what I wrote. I'll rephrase the first sentence you wrote for you:
"So gravity is a fundamental force, but gravity is not a newtonian force. I appear to be accelerating but I appear am not actually accelerating."

There's a lot of technicalities in this though. You are accelerating in relation to objects around you (such as the ground) when you are in free-fall. The gist is that the falling motion is non-inertial, so it is a straight line with a constant speed, but only in relation to the space you are currently in. In relation to all the space around you, your are accelerating. It's both right to say that you are accelerating and not accelerating. In relation to the space you exist in, you are moving straight with constant speed. But in relation to the ground, you are accelerating downwards at 9.82m/s^2. And because you technically aren't accelerating, you aren't subjected to any forces (newtonian ones, so f=ma is not present). When standing on the ground, the ground has to constantly accelerate you up, because constant motion for you would be an accelerating motion going through the ground (to the ground). This is why you can't feel if you are falling if you are in space, because there are no forces. You can feel where down is, because there is a normal force (the ground pushing you up).

You didn't read what I wrote. I'll rephrase the first sentence you wrote for you:
"So gravity is a fundamental force, but gravity is not a newtonian force. I appear to be accelerating but I appear am not actually accelerating."

There's a lot of technicalities in this though. You are accelerating in relation to objects around you (such as the ground) when you are in free-fall. The gist is that the falling motion is non-inertial, so it is a straight line with a constant speed, but only in relation to the space you are currently in. In relation to all the space around you, your are accelerating. It's both right to say that you are accelerating and not accelerating. In relation to the space you exist in, you are moving straight with constant speed. But in relation to the ground, you are accelerating downwards at 9.82m/s^2. And because you technically aren't accelerating, you aren't subjected to any forces (newtonian ones, so f=ma is not present). When standing on the ground, the ground has to constantly accelerate you up, because constant motion for you would be an accelerating motion going through the ground (to the ground). This is why you can't feel if you are falling if you are in space, because there are no forces. You can feel where down is, because there is a normal force (the ground pushing you up).

Thanks for taking the time of going over this with me.
So, gravity is not a newtonian force, the newtonian force is a pseudo force caused by the fact that the earth is a non-inertial frame of reference. It is non-inertial because it bends space-time. Is that correct?

About your second paragraph, you write "the falling motion is non-inertial", isn't that supposed to be "the falling motion is inertial"? A straight line with constant speeds meens no acceleration, which means you're inert? By the way, does this mean if I am free-falling through a vacuum, I am actually observing things from an inertial frame of reference?

What do we call the normal force that the ground is exerting on me while I am standing on it?

How do flat earthers explain the Cavendish experiment without gravity?

Thanks for taking the time of going over this with me.
So, gravity is not a newtonian force, the newtonian force is a pseudo force caused by the fact that the earth is a non-inertial frame of reference. It is non-inertial because it bends space-time. Is that correct?

Yes, that is correct. Earth isn't directly a non-inertial frame of reference because it bends space time, but because it is accelerating in relation to other frame of references (which is however caused by bending of space-time).

About your second paragraph, you write "the falling motion is non-inertial", isn't that supposed to be "the falling motion is inertial"? A straight line with constant speeds means no acceleration, which means you're inert? By the way, does this mean if I am free-falling through a vacuum, I am actually observing things from an inertial frame of reference?

Yeah sorry, I meant inertial. Don't know why I wrote non-inertial, seconds before I wrote that I used translate (not native english speaker) to get it correct. But no, you won't be an inertial frame of reference, at least not as an observer. However, your own bending of space time is so negligible that every piece of your body is an inertial frame of reference to every other part of your body, since all of them moves through roughly the same space (and none of them accelerates, neither inertial or in relation to each other, at least no in any meaningful magnitude). A non-inertial frame of reference is one that is not accelerating relative to another frame in the absence of real forces. That is, despite there being no forces, there is acceleration. An inertial frame of reference is one that is completely free of acceleration in relation to another frame, unless there is a force present. So, acceleration only happens when there is a force. The Coriolis effect is an example of a fictitious force, which makes the object subjected to it and the earth (if we assume an object moving over earth) two non-inertial frames. No forces are present, but there is still acceleration. For a car accelerating along the ground, the car and the ground are inertial frames, because they are accelerating in relation to each other, but that is because of a force. Now technically, even in this case both frames are non-inertial ones. That's because of gravity. Since gravity isn't a force, the car is accelerating down in relation to the ground, but no forces are doing it. However, the ground is pushing the car up, accelerating it up at 9.82m/s^2. So the car is subjected to a force, but DOESN'T accelerate. This also makes the ground and the car non-inertial frames of references. This can be applied to everything, so generally speaking, every frame of reference is non-inertial, which is fundamental in general relativity, which gravity is based on (the gravity we are discussing).

What do we call the normal force that the ground is exerting on me while I am standing on it?

It's called a normal force, and it is a newtonian one, so f=ma is present. Weight is what we call the fictitious force which we get if we insert the gravitational acceleration into the f=ma formula. A normal force is any force which acts perpendicular to the surfaces of two colliding objects.

As the OP has been derailed to just gravity
Consider this:
Object A and object B are in contact with each other, a force is applied between A and B, so that they separate at the rate of  y, they will continue to separate at the speed of y, until there is a force applied upon them. Newton's law of motion is applied.

Now let object A be a person, object B be the earth, the force applied a jump at the speed of y, what is the force that brings the person back down to earth?

On a body moving at constant speed of 60 miles an hour, I jump in the same direction of movement at 1 mph therefore, moving at 61 mph, we'll then continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.

fixed

As the OP has been derailed to just gravity
Consider this:
Object A and object B are in contact with each other, a force is applied between A and B, so that they separate at the rate of  y, they will continue to separate at the speed of y, until there is a force applied upon them. Newton's law of motion is applied.

Now let object A be a person, object B be the earth, the force applied a jump at the speed of y, what is the force that brings the person back down to earth?

on an accelerating body at 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.

I'm getting acceleration and velocity all screwed up when reading your post, sorry. Can you make yourself clearer?

Quote from: MouseWalker on January 29, 2016, 11:30:45 AM

As the OP has been derailed to just gravity
Consider this:
Object A and object B are in contact with each other, a force is applied between A and B, so that they separate at the rate of  y, they will continue to separate at the speed of y, until there is a force applied upon them. Newton's law of motion is applied.

Now let object A be a person, object B be the earth, the force applied a jump at the speed of y, what is the force that brings the person back down to earth?

on an accelerating body at 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.

I'm getting acceleration and velocity all screwed up when reading your post, sorry. Can you make yourself clearer?

i fix it to read
on an body moving at constant speed of 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.
does that help?

Quote from: Master_Evar on January 29, 2016, 12:11:01 PM

Quote from: MouseWalker on January 29, 2016, 11:30:45 AM

As the OP has been derailed to just gravity
Consider this:
Object A and object B are in contact with each other, a force is applied between A and B, so that they separate at the rate of  y, they will continue to separate at the speed of y, until there is a force applied upon them. Newton's law of motion is applied.

Now let object A be a person, object B be the earth, the force applied a jump at the speed of y, what is the force that brings the person back down to earth?

on an accelerating body at 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.

I'm getting acceleration and velocity all screwed up when reading your post, sorry. Can you make yourself clearer?

i fix it to read
on an body moving at constant speed of 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.
does that help?

Yup, I think. It shouldn't matter what speed the body has though (which is part of what confused me), if you jump in any direction away from it with a velocity of 1 mph you would move away from it at 1mph, so long as no gravity or other forces are present.

Quote from: MouseWalker on January 29, 2016, 12:44:56 PM

Quote from: Master_Evar on January 29, 2016, 12:11:01 PM

Quote from: MouseWalker on January 29, 2016, 11:30:45 AM

As the OP has been derailed to just gravity
Consider this:
Object A and object B are in contact with each other, a force is applied between A and B, so that they separate at the rate of  y, they will continue to separate at the speed of y, until there is a force applied upon them. Newton's law of motion is applied.

Now let object A be a person, object B be the earth, the force applied a jump at the speed of y, what is the force that brings the person back down to earth?

on an accelerating body at 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.

I'm getting acceleration and velocity all screwed up when reading your post, sorry. Can you make yourself clearer?

i fix it to read
on an body moving at constant speed of 60 miles an hour,  I jumped at 1 mph therefore moving at 61 mph we'll continue to separate at 1 mph and tell something else happens. Newton's law of motion is applied once more.
does that help?

Yup, I think. It shouldn't matter what speed the body has though (which is part of what confused me), if you jump in any direction away from it with a velocity of 1 mph you would move away from it at 1mph, so long as no gravity or other forces are present.

I fix it once more.
Yes and that is the point I am after.
Can the, TheEngineer dispute this, and answer the question?

Can the, TheEngineer dispute this, and answer the question?

Why is it relevant what would happen if Earth is moving with constant velocity? If Earth is accelerated your description is wrong.

I would like his comment to the weird misconception of f=a/m of his that i pointed out though.

Gravity is the phenomenon which causes acceleration between bodies with mass.

You left out objects without mass.  Surprised you didn't know this.  Oh, wait, no I'm not; you're an idiot.

The force of gravity is weight.

The force of gravity doesn't exist.  I don't know how many times I have to say this.

The pure definition of acceleration is a=dv/dt.

Yep.  That's what I said.  I see your reading comprehension has not improved. 

Remember what I said about these games making you look foolish?  This is another example.

Oh, and:

Gravity is not a force...gravity is also a force

In the same post!  LOL!

Oh, and one more:

accelerating you upwards at 9.82m/s. And the ground below the ground is accelerating that ground up at 9.82m/s.

Idiot.

If I jump off something the accellerometer reads 9.8.

So you didn't actually perform the experiment, did you?

Can the, TheEngineer dispute this, and answer the question?

Sure:
In your thought experiment, the car has a constant velocity.  Therefore, you are never overtaken by the car.

In the FE, the FE has a constant acceleration.  Therefore, you are overtaken by the FE.

Quote from: MouseWalker on January 27, 2016, 09:15:27 PM

Saying gravity does not exist, in your own words, is not proof.
Where is your proof that gravity does not exist?

Seeing as I can make it disappear by stepping off a ladder or jumping out of a plane pretty much shows that gravity is not real, but is a fictitious force.

Actually I miss this, make it disappear?, not happening, you will soon learn how real gravity is when you hit the ground.
Lets get back to the OP explain the Hawaiian island chain, what forces created it? Why a chain of islands?

And how was the challenger deep created?


And a subduction zone is going down not up.

It's called a normal force, and it is a newtonian one, so f=ma is present. Weight is what we call the fictitious force which we get if we insert the gravitational acceleration into the f=ma formula. A normal force is any force which acts perpendicular to the surfaces of two colliding objects.

Ok, thanks for explaining!
One more question: What causes the normal force that is pushing me up? And is that force the exact opposite of the pseudo-force of gravity?

I still wonder if saying "The force of gravity doesn't exist" is actually accurate from an epistemological point of view. Does a more inclusive model, in which the force is identified as a pseudo-force, mean that it isn't part of empirical reality, i.e. it doesn't exist? Or does it merely mean that it does exist in a given frame of reference, but is the result not of physical interaction within the frame of reference but of the acceleration of the frame itself?

Basically, does the empirical truth look different from different frames of reference, or is it defined without any frame of reference at all?

Ok, thanks for explaining!
One more question: What causes the normal force that is pushing me up? And is that force the exact opposite of the pseudo-force of gravity?

It is caused by the inertia of the ground - it is resisting your accelerating motion. It is not always exact opposite:

mg is the pseudo-force of gravity, the weight of the object. mg cos0 is the part of the mg force which acts perpendicular onto the surface, and N is the normal force, and is equal and opposite to mg cos0. mg sin0 is the other part of the mg force, which would cause acceleration down the slope. f is the friction, and equals normal force * coefficient (but won't ever be greater than mg sin0). Out of all of these forces, only the normal force and friction are real forces, the other are pseudo-forces. When the net force of friction, normal force and mg = 0, the object is at rest.

I still wonder if saying "The force of gravity doesn't exist" is actually accurate from an epistemological point of view. Does a more inclusive model, in which the force is identified as a pseudo-force, mean that it isn't part of empirical reality, i.e. it doesn't exist? Or does it merely mean that it does exist in a given frame of reference, but is the result not of physical interaction within the frame of reference but of the acceleration of the frame itself?

Basically, does the empirical truth look different from different frames of reference, or is it defined without any frame of reference at all?

It looks different from different frames of references. From our point of view, it is the earth that is accelerating towards us at 9.82m/s^2. Weight/the force of gravity isn't real, it is not physical, but only hypothetical. It is a number we get when we try to make two non-inertial frames of references into two inertial ones. But then, this assumes that general relativity is ENTIRELY right in it's modelling. It might just be that general relativity has the numbers right, but that gravity is mediated according to the standard model. I.e., there is a boson named the Graviton, which causes particles to be drawn to bodies with mass. If this is the case, gravity is indeed a force.

You left out objects without mass.  Surprised you didn't know this.  Oh, wait, no I'm not; you're an idiot.

Nah, just a mistake, you know those things which everyone makes once in a while.

The force of gravity doesn't exist.  I don't know how many times I have to say this.

You have to say it 0 times for me to get it. Oh wait, why are you still saying this?
Weight doesn't exist either, because weight and the force of gravity is the exact same thing. It seems you didn't know this, since you answered so stupidly.

Yep.  That's what I said.  I see your reading comprehension has not improved.

Nope, you said:

1. Coordinate acceleration is the rate of change of velocity.
2. Physical acceleration is the acceleration of a body relative to an inertial condition.

Can't find a=dv/dt anywhere in there.  (Yes, I am aware that 1 means basically the same thing, but I was looking for the mathematical term).

But, we can agree then that a=dv/dt then?

Oh, and:

Quote from: Master_Evar on January 29, 2016, 12:02:18 AM

Gravity is not a force...gravity is also a force

In the same post!  LOL!

Oh, and one more:

Quote from: Master_Evar on January 29, 2016, 12:02:18 AM

accelerating you upwards at 9.82m/s. And the ground below the ground is accelerating that ground up at 9.82m/s.

Idiot.

You are an idiot: "However, gravity is also a force, but not as described by newtonian mechanics, but as described by the standard modell."

Apparently, you have no idea what this sentence means. Which is just further evidence that you aren't qualified for discussing gravity.

If we continue discissing semantics, we will get nowhere.

In GR gravity is a fictitious force. TheEngineer is correct about that. That doesnt mean that it is not real in a physical sense, we can measure it, just like we can measure centrifugal force, it just means that it is a byproduct of accelerated movement, and would disappear if there was no acceleration. Thats not really worth discussing, thats just how it is if you accept GE.

The thing is, it doesnt really change anything when it comes to describing movements in the sense you guys are discussing here. Thats what the equivalence principle say. The two ways of thinking gives the same results when talking about normal human movement on Earth. What makes it hard to fathom is that the concept of acceleration is different too, as freefall in GR means something different. But still, the two ways of describing things gives the same results in the context of the discussion in this thread.

There seem to be some rather imaginative misconceptions about what this shift means in here, on both sides. For instance TheEngineers claim that f=a/m can show that we are accelerated. A misconception i pointed out and he conviniently completely ignored. Or the that the idea that we are accelerating outwards everywhere on a sperical earth would somehow imply that earth has to grow.