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Deepak Kapur

Matter or Forces

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When I hold a ball in my hand...

 

What is it made of?

 

More of matter or more of forces? In other words what accounts for the mass of a body, the atoms, nucleons, electrons etc. or the forces that hold them together?

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The mass is mainly due to the energy holding it together: overhwelmingly the binding energy of the quarks in the protons and neutrons; a small amount from the energy holding the nucleus together (which is released in nuclear fission/fusion); and tiny amounts from the Higgs mechanism and chemical bonds (electrostatic forces).

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Strange

 

and chemical bonds (electrostatic forces).

 

 

Are you suggesting that matter that is chemically bonded has more mass than matter that is not chemically bonded?

 

I note that this is the classical physics forum, so Deepak are you looking for a particle physics answer or a classical answer?

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Are you suggesting that matter that is chemically bonded has more mass than matter that is not chemically bonded?

 

I note that this is the classical physics forum, so Deepak are you looking for a particle physics answer or a classical answer?

 

 

Both would be great!

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Are you suggesting that matter that is chemically bonded has more mass than matter that is not chemically bonded?

 

If there is more energy in the bonded form, yes.

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Most of the mass of a given nucleon comes from the binding energy between the quarks making up that nucleon. It is something like 100 times heavier than just the rest mass of the quarks and the gluons are of course massless.

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Both would be great!

 

 

So you want to have your cake and eat it!

 

:P

 

Classically the component particles are the only contributors to the mass.

 

Forces from any source act on the mass of the component particles or their aggregates, but do not change them.

 

Modern physics does not work in terms of force at all, but considers mediating exchange particles, or other effects such as spacetime curvature instead. Since this side of physics is still undergoing rapid development you really need to ask that question in the modern physics section and understand that any answer will keep changing, depending upon which theory you are studying.

 

 

 

 

 

 

Studiot

Are you suggesting that matter that is chemically bonded has more mass than matter that is not chemically bonded?

 

Strange

If there is more energy in the bonded form, yes.

 

 

I was aware of the difference due to nuclear binding energy, but not aware of any due to chemical bonds. Do you have any references?

Edited by studiot

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Thank you for the link, strange.

 

It does rather disagree with itself in the discussion.

Worse the first answer listed is actually wrong.

 

My copy of Semat: Atomic and Nuclear Physics has 'Mass defect' as due to the binding energy of the nucleus, not any chemical bond the atom may enter into.

 

This effect is measurable.

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Thank you for the link, strange.

 

It does rather disagree with itself in the discussion.

Worse the first answer listed is actually wrong.

 

My copy of Semat: Atomic and Nuclear Physics has 'Mass defect' as due to the binding energy of the nucleus, not any chemical bond the atom may enter into.

 

This effect is measurable.

It probably reads as this or similar the thing that gets people is the mass of a bound system is lower than its constituent components. binding energy =mass change*c2 the energy loss is used to maintain the bond (binding energy) upon breaking the chemical bond the binding energy is released as heat. However the energy to break the bonds is supplied by the environment. So there is a chemical bond effect on mass,

 

http://en.wikipedia.org/wiki/Binding_energy

Edited by Mordred

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Thank you for the article Mordred.

 

this seems self contradictory to me.

 

 

Exothermic chemical reactions in closed systems do not change mass, but become less massive once the heat of reaction is removed, though this mass change is much too small to measure with standard equipment.

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My copy of Semat: Atomic and Nuclear Physics has 'Mass defect' as due to the binding energy of the nucleus, not any chemical bond the atom may enter into.

The term is used for that situation simply because there is a measurable change in mass. But there is nothing qualitatively different between nuclear binding energy and chemical energy (or thermal energy). It is all energy and all equivalent to mass.

This seems self contradictory to me.

 

 

Note sure why. It is the loss of energy that causes a change in mass. In a closed system there is (by definition) no loss of energy. Allow the energy to leave and the mass is reduced.

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. But there is nothing qualitatively different between nuclear binding energy and chemical energy (or thermal energy). It is all energy and all equivalent to mass.

 

 

Just saying this doesn't make it so.

 

And no I do not agree that the nuclear binding energy is qualitatively the same ie it does not spring from the same mechanism.

 

In a chemical reaction, if the products are heated by the reaction then the molecules are moving faster.

That is they experience an increased relative velocity.

 

So, as with any moving mass, they will appear to gain mass to that which they are moving relative to.

 

But this would also be true if they were just heated up some other way and did not react chemically. That is the same effect could be realised without changing the bonds.

 

So how can you attribute the mass change to the bond energy?

 

By contrast the nuclear particles are not in such vigorous relative motion and the forces in play are from a different source.

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ok I have to ask which form of mass are we discussing?

 

-inertial mass measures an object's resistance to changes in velocity m=F/a. (the object's acceleration)
-Active gravitational mass measures the gravitational force exerted by an object.
-Passive gravitational mass measures the gravitational force experienced by an object in a known gravitational field.
-Mass-Energy measures the total amount of energy contained within a body, using E=mc²

-atomic mass

 

please note I did not mention rest mass eo =moc2

http://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation

I assume were discussing mass-energy which is what myself and Strange have been discussing.


 

Just saying this doesn't make it so.

 

And no I do not agree that the nuclear binding energy is qualitatively the same ie it does not spring from the same mechanism.

 

In a chemical reaction, if the products are heated by the reaction then the molecules are moving faster.

That is they experience an increased relative velocity.

 

So, as with any moving mass, they will appear to gain mass to that which they are moving relative to.

 

But this would also be true if they were just heated up some other way and did not react chemically. That is the same effect could be realised without changing the bonds.

 

So how can you attribute the mass change to the bond energy?

 

By contrast the nuclear particles are not in such vigorous relative motion and the forces in play are from a different source.

 

your supplying the energy to break the bonds, once the bonds are broken your now measuring the constituent components whose totals will be higher than the previous bound system, however if you measure those constituents prior to allowing them to cool back to a normal state your measuring its total energy. Which isn't the same as measuring the change due to a chemical bond. You need to renormalize the system to get an accurate mass change due to the binding energy

 

"Since all forms of energy exhibit rest mass within systems at "rest" (that is, in systems which have no net momentum), the question of where the missing mass of the binding energy goes, is of interest. The answer is that this mass is lost from a system which is not closed. It transforms to heat, light, higher energy states of the nucleus/atom or other forms of energy, but these types of energy also have mass, and it is necessary that they be removed from the system before its mass may decrease. The "mass deficit" from binding energy is therefore removed mass that corresponds with removed energy, according to Einstein's equation E = mc2. Once the system cools to normal temperatures and returns to ground states in terms of energy levels, there is less mass remaining in the system than there was when it first combined and was at high energy. Mass measurements are almost always made at low temperatures with systems in ground states, and this difference between the mass of a system and the sum of the masses of its isolated parts is called a mass deficit. Thus, if binding energy mass is transformed into heat, the system must be cooled (the heat removed) before the mass-deficit appears in the cooled system. In that case, the removed heat represents exactly the mass "deficit", and the heat itself retains the mass which was lost (from the point of view of the initial system). This mass appears in any other system which absorbs the heat and gains thermal energy.[6]"

 

from the wiki article I posted

Edited by Mordred

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Just saying this doesn't make it so.

 

And no I do not agree that the nuclear binding energy is qualitatively the same ie it does not spring from the same mechanism.

 

In a chemical reaction, if the products are heated by the reaction then the molecules are moving faster.

That is they experience an increased relative velocity.

 

So, as with any moving mass, they will appear to gain mass to that which they are moving relative to.

 

But this would also be true if they were just heated up some other way and did not react chemically. That is the same effect could be realised without changing the bonds.

 

So how can you attribute the mass change to the bond energy?

 

By contrast the nuclear particles are not in such vigorous relative motion and the forces in play are from a different source.

 

It doesn't matter what form the energy is: you can heat it up, increase the energy in chemical bonds or increase the energy in nuclear bonds. It is just energy. And therefore equivalent to mass.

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It doesn't matter what form the energy is: you can heat it up, increase the energy in chemical bonds or increase the energy in nuclear bonds. It is just energy. And therefore equivalent to mass.

 

 

Repetition does not strengthen verification.

 

That is the province of reasoned argument.

 

In your previous post you claimed that they were qualititatively the same, but haven't addressed my comment on that. For instance is gravitational energy qualitatively the same since it arises from a distortion of space?

 

Mordred has made a good point about which mass.

I noted that the increased mass appears to observers in (increased) relative motion to the molecules concerned.

Do the molecules concerned observe any increase in their own mass?

Why should there be an increase in mass when there is no increase in relative motion? What is the mechanism for this?

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Repetition does not strengthen verification.

 

http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

http://plato.stanford.edu/entries/equivME/

 

I just assumed this was common knowledge.

 

 

is gravitational energy qualitatively the same since it arises from a distortion of space?

 

Yes. This is one of the reasons that gravity is non-linear in GR: the energy of the gravitational field contributes to the gravitational field.

 

 

Do the molecules concerned observe any increase in their own mass?

 

Not in the case of relativistic mass (because they are not moving relative to themselves).

 

 

Why should there be an increase in mass when there is no increase in relative motion? What is the mechanism for this?

 

Mass energy equivalence (see above).

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Yes. This is one of the reasons that gravity is non-linear in GR: the energy of the gravitational field contributes to the gravitational field.

 

So if I took a mass and elevated it according to that old thermodynamic chestnut of Joules experiment (infinitely slowly) would it gain in mass?

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So if I took a mass and elevated it according to that old thermodynamic chestnut of Joules experiment (infinitely slowly) would it gain in mass?

 

Good question. I think the answer is that it would lose mass. After all, raising a photon from the surface of the Earth lowers its energy (red shifts it).

http://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment

 

But, of course, that change in energy (mass) is relative to an observer on Earth - someone travelling with the mass would see no change.

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If we have molecule of water H2O at altitude 0, sea level, we need to give it energy to rise it to 1m, and even more energy to turn it to vapor and reach cloud altitude. If this molecule lose its kinetic energy (f.e. give it to N2 or O2), it will turn back to fluid state and will have to fall down to the ground of Earth. Airplane, satellite, rocket or anything flying must to not lose its kinetic energy to not fall down.

In high energy physics, in particle accelerators, kinetic energy of particles accelerated to nearly speed of light are turned in collision to another proton and antiproton pair

I don't know about you, but for me it's enough proof that it's real thing.

 

Is kinetic energy the real thing?

For somebody touching water with 0 C, and later water with 100 C, or touching metal at 0 C then 100 C, he can really see & fell difference.

 

N2 molecule has 4.65*10^-26 kg, so kinetic energy with v=340 m/s is just 2.69*10^-21 J (predicted change in mass of molecule 2.99*10^-38 kg)
O2 molecule has 5.3137*10^-26 kg, so kinetic energy with v=340 m/s is just 3.07*10^-21 J (predicted change in mass of molecule 3.417*10^-38 kg)

Edited by Sensei

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I have something to ask ( though it seems foolish to me also).

 

But still.........

 

 

I have two magnets A & B.

 

I can move A or B wherever I want. Now, I bring them close and they stick to each other.

 

 

Can I say that now A & B both have more energy, as I am not able to move them?

 

If I want to move A, I have to use a lot more energy that before. Same is the case with B.

 

Thanks.

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