[timey (OP)]

What is the difference between gravity potential, and gravity potential energy?

Do they have different values?

[Janus]

What is the difference between gravity potential, and gravity potential energy?

Do they have different values?

gravitational potential is gravitational potential energy per unit of mass.     If the gravitational potential energy is measured in kgm^2/s^2 then the gravitational potential is m^2/s^2 .  Thus if you have two masses in the same position in a gravity field and one is twice the mass of the other, they both have the same gravitational potential, but one would have twice the gravitational potential energy.

[jeffreyH]

This is exactly why dimensional analysis is so important.

[timey (OP)]

What is the difference between gravity potential, and gravity potential energy?

Do they have different values?

gravitational potential is gravitational potential energy per unit of mass.     If the gravitational potential energy is measured in kgm^2/s^2 then the gravitational potential is m^2/s^2 .  Thus if you have two masses in the same position in a gravity field and one is twice the mass of the other, they both have the same gravitational potential, but one would have twice the gravitational potential energy.

So Janus - In the case of light falling towards body M, we can understand that as the photons are the equal of each other at each coordinate within the gravity potential well, and all travelling at the same speed, ie: c, that all photons are affected equally.

And that when m's of differing mass value are free falling towards M, the gravity potential, and resulting gravity potential energy decrease for m in free fall is going to be differing for m's of differing values of mass.
The kinetic energy values will also be differing for differing values of m in free fall.
Yet despite the momentum (?) differences between differing mass values in free fall, all values of m accelerate at the same rate in the decreasing gravity potential of the g-field.
I know you cannot explain why this happens because it is not currently known why all values of m accelerate at the same rate in free fall...

But...  the mass or relativistic mass value for m and light, respectively, are used in calculation to describe momentum, or p in the maths.

What exactly is the physical description of momentum?

[Bill S]

   So Janus - In the case of light falling towards body M, we can understand that as the photons are the equal of each other at each coordinate within the gravity potential well, and all travelling at the same speed, ie: c, that all photons are affected equally.

This is probably nit-picking, but isn’t it usual to consider light as waves, when travelling, and as photons only when observed?

Does that make any difference to your animadversions?

[timey (OP)]

You make a good point Bill that is indeed highly relevant to the ultimate direction of my thinking, but at present this is me picking through the mathematics and understanding the physical nature of what those maths are describing.

At the moment I am lacking a physical description for the use of p in the maths.  Clearly there are several means of deriving p mathematically involving:
p = hv(bar)
where vbar is:
v/a
and h is Planck's h constant

Or
p = mv

Both descriptions seem to point to p being an accelerative derivation (or should I say deduction)...

I'm interested in what Janus can tell me about what a description of momentum, or p in the maths, actually physically consists of...

...but am also now mildly interested in what an animadversion is.  I've not come across that before (quick google) ... Ah, criticism!
No Bill, you have me all wrong!  I am a curious mind, is all that is going on here.  It is only people who interpret my questions as being non-understandings of the subject matter, rather than an intrinsic interest in matters that cannot be explained by the current remit, who do rather seem to feel that I am being unwarrantedly critical.  It is not a criticism to systematically dissemble a system into cause and effect.  As far as I'm concerned it is indeed a complement to the system...
For instance Rubik cubes are well boring!

[jeffreyH]

For a simple harmonic oscillator such as a pendulum you have a force constant k.
k = 4pi²mT^-2 where m is the mass and T the time period of the oscillations. Since k is constant then mass and T must not vary in a way that changes the value of k.
https://en.m.wikipedia.org/wiki/Harmonic_oscillator

[jeffreyH]

Then F = ma = -kx

[jeffreyH]

Escape velocity is given by
Δv = sqrt(2GM/Δr)
then potential is
ΔU =GM/Δr

[timey (OP)]

I am looking for a description (in words, not maths) of what is physically occurring when p is applied in the maths.

For instance, acceleration being denoted as a is applied in maths, this is a description of the physical action of a speed becoming faster to cover more distance in less time.

What is the physical description of momentum?

[jeffreyH]

This is as basic as it can get.
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/kinetic_energy/momentumrev1.shtml

[timey (OP)]

Oh for goodness sake Jeff - grow up!

Momentum is being calculated in the way I mentioned many posts ago.

What is the physical action of the use of p in the maths?
Clearly there is a force that is causing momentum and the use of momentum, ie: p, is describing this force mathematically...
But what is that force of momentum please?
Can you give me a physical description?

[JohnDuffield]

Perhaps I can assist?
 

So Janus - In the case of light falling towards body M, we can understand that as the photons are the equal of each other at each coordinate within the gravity potential well, and all travelling at the same speed, ie: c, that all photons are affected equally.

All photons are affected equally, but rather counter-intuitively, the descending photon slows down. In similar vein, the ascending photon speeds up. Check out this PhysicsFAQ article  by relativists Don Koks: Is The Speed of Light Everywhere the Same? The answer is no. See this:

So consider the question: "Can we say that light confined to the vicinity of the ceiling of this room is travelling faster than light confined to the vicinity of the floor?".  For simplicity, let's take Earth as not rotating, because that complicates the question!  The answer is then that (1) an observer stationed on the ceiling measures the light on the ceiling to be travelling with speed c, (2) an observer stationed on the floor measures the light on the floor to be travelling at c, but (3) within the bounds of how well the speed can be defined (discussed below, in the General Relativity section), a "global" observer can say that ceiling light does travel faster than floor light.

And that when m's of differing mass value are free falling towards M, the gravity potential, and resulting gravity potential energy decrease for m in free fall is going to be differing for m's of differing values of mass.

The gravitational potential energy is converted into kinetic energy. Having a mass of a different size is only like having a different number of unit masses.

I know you cannot explain why this happens because it is not currently known why all values of m accelerate at the same rate in free fall.

I didn't think there was any mystery to that.

But...  the mass or relativistic mass value for m and light, respectively, are used in calculation to describe momentum, or p in the maths.

Relativistic mass is a measure of energy.

What exactly is the physical description of momentum?

A time-based measure of resistance to change-in-motion. Kinetic energy is a distance-based measure. Think of a cannonball in space moving at 1000m/s. When you apply a constant braking force you bring the cannonball to a halt in x metres, which is your kinetic energy measure, and y seconds, which is your momentum measure. Divide by c which is distance over time to go from one to the other. People tend to say a cannonball has kinetic energy and momentum, but you can't remove one without the other. Because they're two aspects of the same thing, called energy-momentum.

[jeffreyH]

Oh for goodness sake Jeff - grow up!

Momentum is being calculated in the way I mentioned many posts ago.

What is the physical action of the use of p in the maths?
Clearly there is a force that is causing momentum and the use of momentum, ie: p, is describing this force mathematically...
But what is that force of momentum please?
Can you give me a physical description?

I was trying to help. Seeing as you wanted a description in words I gave you that. Read what John posted. That should do. I'm done.

[jeffreyH]

John if you don't even know the difference between velocity, acceleration and force I would give up now.


Before I forget. When you are applying your constant braking which direction is the acceleration vector pointing? Now that is a simple one. If you can't answer that then you should give up now.

[jeffreyH]

Oh for goodness sake Jeff - grow up!

Momentum is being calculated in the way I mentioned many posts ago.

What is the physical action of the use of p in the maths?
Clearly there is a force that is causing momentum and the use of momentum, ie: p, is describing this force mathematically...
But what is that force of momentum please?
Can you give me a physical description?

Just one last point before I go. If you have constant momentum there is no force. It follows Newton's laws.

[timey (OP)]

Oh for goodness sake Jeff - grow up!

Momentum is being calculated in the way I mentioned many posts ago.

What is the physical action of the use of p in the maths?
Clearly there is a force that is causing momentum and the use of momentum, ie: p, is describing this force mathematically...
But what is that force of momentum please?
Can you give me a physical description?

Just one last point before I go. If you have constant momentum there is no force. It follows Newton's laws.

Correct, that is exactly what I deduce.

But I'd still like a full description in words of the physical action being described when using p in the maths and do hope that Janus will give answer.

[timey (OP)]

Thank you John.  Btw, I am aware that if one uses duration of a GR time dilated second to calculate the speed of light via, then it could be said that light slows down closer to mass, as a time variant, not a speed variant.
This is of course interesting to me, but despite your description of momentum, I am no closer to an explanation of 'why' p is being used in the maths.

I don't see the requirement in repeating that which I have already said, and I too have read the Einstein papers.

I want a description of the physical cause for momentum being used as a  means of manipulating the maths.

a = acceleration, which can be physically described as being caused by a speed that is getting faster and resulting in a distance covered in less time
v = a speed being caused by a force, and resulting in distance being covered in a specific time
p = momentum being caused by ? and resulting in ?

My interest is born of the Planck Einstein relation that also relates to DeBroglie, and I want to understand what p is physically describing within the manipulation of those maths.

My question arising from Janus's answer is very specific, and having had the title question answered by Janus, the question I am asking now is specifically as I state and it is that and nothing else that I require an answer to, at this time.

[jeffreyH]

The value of v is not being caused by a force since it is not an acceleration.

[jeffreyH]

God help you if you ever try to tackle Maxwell's equations.