String Trimmer Batteries - same weight charged and empty

[barbos]

mc^2 is not a factor. That energy is accessible in nuclear reactions. Not in ordinary chemical reactions.

It applies to both cases equally, E=mc² is fundamental.

It looks, to me, like he was denying that m=E/c² for any energy too.

So we have backpedaling here?
There is nothing really that special about nuclear energy except it is orders of magnitude larger than chemical.
I mean, number of neutrons/protons does not change in nuclear fission, so according to him mass should be the same.

 

[Wiploc]

Actually, this is all incorrect because H2O should be lighter than H+H+O. What happened is that you were not careful with isotopes

I just asked google for atomic weights.

But you're right that H20 should be lighter than H+H+O. Burning hydrogen to get water is exothermic. To go the other way, we'd have to put energy back in.

Which, Steve, means that a hydrogen/oxygen battery would be discharged (and lighter) when the contents were in the form of water, and charged (and heavier) when in the form of hydrogen and oxygen.

 

[steve_bank]

Yes. It used to be lead acid car batteries had to have water added periodically. During charge and discharge the mass is all accounted for. The chemical equations are balanced.

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

wake a sealed D cell battery and connect a resistor across it. Current flows, power is consumed, battery discharges.

Chemical energy is converted to work moving electrons and is converted to heat. The increase in heat in the resistor increases photon emission.

In the process where does E=mc^2 equate to loss of mass in the battery? The claim is there is loss of mass occurs not accounted for in chemical equations.

 

[bilby]

Yes. It used to be lead acid car batteries had to have water added periodically.

Due to evaporation. Nothing at all to do with the problem at hand.

During charge and discharge the mass is all accounted for.

Yes - and some of it is due to the stored energy. Not much. But not none.

The chemical equations are balanced.

No shit, Sherlock.

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

No, it didn't. That's entirely your misunderstanding. There are the same number of electrons in both cases; But the mass of the charged battery is, nevertheless, greater than the mass of the discharged battery. You can't simply add up the masses of the particles, you have to include the mass due to the energy binding the various atoms together - because that's where the usable energy in the battery is coming from.

wake a sealed D cell battery and connect a resistor across it. Current flows, power is consumed, battery discharges.

Chemical energy is converted to work moving electrons and is converted to heat. The increase in heat in the resistor increases photon emission.

In the process where does E=mc^2 equate to loss of mass in the battery? The claim is there is loss of mass occurs not accounted for in chemical equations.

The loss of mass is in the loss of heat to the environment. How can heat be lost to the environment without a change in mass, if E=mc² ?

Energy leaves the system. So if E=mc², mass (equal to E/c²) must also leave the system.

If the system lost energy without changing its mass, then that would demonstrate that E=mc² is not true (and would win you a Nobel).

 

[skepticalbip]

... snip ...

In the process where does E=mc^2 equate to loss of mass in the battery? The claim is there is loss of mass occurs not accounted for in chemical equations.

You are making the question much more convoluted than it is. The question is, does adding energy to a system increase its mass?

Newton said no it doesn't. That mass and energy are independent and unrelated things.
Einstein said absolutely yes, adding energy to a system increases its mass or removing energy decreases its mass (derived from his special theory of relativity).

Although Einstein was closer to reality, Newton was so fucking close in our every day human scale existence and his error is so insignificant for normal applications that we teach and use his physics rather then Einstein's because it is so much more simple to use. Newton was so close that it took science three hundred years to even notice the error.

On the nuclear scale, the nuclear binding energy is a significant part of the mass of an atom... the reason nuclear reactors work. On the cosmic scale, dark energy is responsible for ~68% of the mass of the universe.

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

Mass–energy equivalence

... the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = ~3×108 m/s) squared. Similarly, anything having energy exhibits a corresponding mass m given by its energy E divided by the speed of light squared c2.

 

[Wiploc]

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

That doesn't work. If more electrons left the battery than returned, then the battery would be positively charged.

If that were the case, then electrons would be drawn to the battery until that situation was rectified. The original number of electrons would return.

 

[bilby]

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

That doesn't work. If more electrons left the battery than returned, then the battery would be positively charged.

If that were the case, then electrons would be drawn to the battery until that situation was rectified. The original number of electrons would return.

Yeah, but he has this crazy idea that if you add up the number of electrons, protons, and neutrons in a battery and multiply each by the mass of a free particle (electron, neutron or proton), then you will get the exact mass of the battery, and that changing the chemistry (and therefore the energy represented by the bonds between atoms) will have no effect.

That we have known for over a century that this is NOT the case doesn't seem to register.

 

[steve_bank]

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

That doesn't work. If more electrons left the battery than returned, then the battery would be positively charged.

If that were the case, then electrons would be drawn to the battery until that situation was rectified. The original number of electrons would return.

In passive electrical theory it is generally said current or charge wants to return to the source. It is an expression of conservation.

 

[steve_bank]

... snip ...

In the process where does E=mc^2 equate to loss of mass in the battery? The claim is there is loss of mass occurs not accounted for in chemical equations.

You are making the question much more convoluted than it is. The question is, does adding energy to a system increase its mass?

Newton said no it doesn't. That mass and energy are independent and unrelated things.
Einstein said absolutely yes, adding energy to a system increases its mass or removing energy decreases its mass (derived from his special theory of relativity).

Although Einstein was closer to reality, Newton was so fucking close in our every day human scale existence and his error is so insignificant for normal applications that we teach and use his physics rather then Einstein's because it is so much more simple to use. Newton was so close that it took science three hundred years to even notice the error.

On the nuclear scale, the nuclear binding energy is a significant part of the mass of an atom... the reason nuclear reactors work. On the cosmic scale, dark energy is responsible for ~68% of the mass of the universe.

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

Mass–energy equivalence

... the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = ~3×108 m/s) squared. Similarly, anything having energy exhibits a corresponding mass m given by its energy E divided by the speed of light squared c2.

I think you are misinterpreting AE. Energy does not have an independent reality Energy is work derived by relative states of matter.

Water at the top of a waterfall has gravitational potential energy that can turn a turbine to do work. E=mc^2 is potential energy in the atomic structure that is re;eased through fiddion.


Consider a tank 100ft above and empty tank. Water runs through turbine doing work, gravitational energy is converted to say electric energy. When the high tank is empty all mass of water and all potential energy, heat, and work are accounted for. LOT. Mass of the water does not change.

I put high pressure steam into a steam driven machine. Both energy and mass are added to the system.

We treat energy and mass as separate variables. That is the way it is defined in SI. There is the kilogram and the Joule. Work, heat, and energy are all expressed in Joules. E = mc^2 is in Joules.If I add steam to a system the energy is in terms of mass and temperature. As the stem cools energy drops but mass stays the same.

You can look up Joule's paddle wheel experiment from the 19th century. It equated work, heat, and energy in equivalent units. A giant leap. The most fundamental relationship in science and especially engineering.

 

[skepticalbip]

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

That doesn't work. If more electrons left the battery than returned, then the battery would be positively charged.

If that were the case, then electrons would be drawn to the battery until that situation was rectified. The original number of electrons would return.

In passive electrical theory it is generally said current or charge wants to return to the source. It is an expression of conservation.

If that is actually said then the someone saying it should be flogged. Current or charge can only flow through a closed loop in electronic circuits.

 

[skepticalbip]

A simple D cell is sealed. The problem claimed less electrons returned to the battery than left therefore the battery would be lighter discharged.

That doesn't work. If more electrons left the battery than returned, then the battery would be positively charged.

If that were the case, then electrons would be drawn to the battery until that situation was rectified. The original number of electrons would return.

In passive electrical theory it is generally said current or charge wants to return to the source. It is an expression of conservation.

If that is actually said then the someone saying it should be flogged. Current or charge can only flow through a closed loop in electronic circuits would be a better description. The reason that 'loop analysis' is a common analytical technique in electronics.

 

[Loren Pechtel]

Consider a tank 100ft above and empty tank. Water runs through turbine doing work, gravitational energy is converted to say electric energy. When the high tank is empty all mass of water and all potential energy, heat, and work are accounted for. LOT. Mass of the water does not change.

Newton doesn't see the change in the mass of the water. Einstein does. The water is now deeper in a gravity field. We're getting into General Relativity's domain, I'm not qualified to go deeper.

 

[steve_bank]

Adding you can add enrgy to a system without adding mass. Wind up trhe spring of a mechanical clock and you have added energy to the system but no mass.

I hold a baseball in hand. It has potential, kinetic, and nuclear energy. Total energy E = PE + KE + mc^2.
.

I throw the ball in the air adding PE and KE. Total energy is still PE + KE + mc^2. Energy comes and goes mc^2 does not change.

 

[steve_bank]

Gravitational energy can show up as potential energy or kinetic energy. I hold a bucket of water and it has gravttaional potential energy. I spill the water and it has kinetic energy from acceleration.

'gravity well' is a red herring. It is the 'gravity well; that adds energy to the water. The kinetic energy at any poibnt is calculated by solving the differential equation.

We normally assume g is constant because it changes little over typical distances. However you could easily add a second order component to account for dg/dh.

 

[steve_bank]

In passive electrical theory it is generally said current or charge wants to return to the source. It is an expression of conservation.

If that is actually said then the someone saying it should be flogged. Current or charge can only flow through a closed loop in electronic circuits would be a better description. The reason that 'loop analysis' is a common analytical technique in electronics.

Technically it is called Kirchoff's voltage and current laws. Both expressions of conservation. We tend to talk in metaphor, analogy, and anthropomorphize circuits and systems. Makes communication easier.

Hook a resistor across a battery and we would say the battery 'sees' a load. AQlways talking mathematical and technically perfect is cumbersome.

If you want to get into analytical techniques start a thread.

 

[bilby]

Adding you can add enrgy to a system without adding mass.

Nope. You can't.

Wind up trhe spring of a mechanical clock and you have added energy to the system but no mass.

No, you haven't.

I hold a baseball in hand. It has potential, kinetic, and nuclear energy. Total energy E = PE + KE + mc^2.
.

Nuclear energy isn't the only energy that is equivalent to mass. If it was, nuclear reactors (and natural radioactive decay) would violate the first law of thermodynamics.

I throw the ball in the air adding PE and KE. Total energy is still PE + KE + mc^2. Energy comes and goes mc^2 does not change.

You are wrong. c² is fucking huge, so the change in m is fucking minuscule. But it's real. And it's important, because E=mc² is absolutely fundamental to reality as we observe it.

 

[bilby]

In passive electrical theory it is generally said current or charge wants to return to the source. It is an expression of conservation.

If that is actually said then the someone saying it should be flogged. Current or charge can only flow through a closed loop in electronic circuits would be a better description. The reason that 'loop analysis' is a common analytical technique in electronics.

Technically it is called Kirchoff's voltage and current laws. Both expressions of conservation. We tend to talk in metaphor, analogy, and anthropomorphize circuits and systems. Makes communication easier.

Not if you are communicating with people who understand basic 20th century physics. Then it makes you come across as a stubbornly microcephalic ignoramus with an irrational penchant for animism. So if that's not what you were trying to communicate, it would appear to have made communication easier only for communicating with idiots.

Hook a resistor across a battery and we would say the battery 'sees' a load. AQlways talking mathematical and technically perfect is cumbersome.

But doing otherwise is wrong.

Maybe not wrong enough for some crude engineering purposes; But wrong nonetheless.

And when you mistake your engineering rules of thumb for technical perfection, you end up believing stupid shit like "E=mc² only applies to atomic energy". Which it absolutely does not.

 

[Jokodo]

Adding you can add enrgy to a system without adding mass. Wind up trhe spring of a mechanical clock and you have added energy to the system but no mass.

I hold a baseball in hand. It has potential, kinetic, and nuclear energy. Total energy E = PE + KE + mc^2.
.

I throw the ball in the air adding PE and KE. Total energy is still PE + KE + mc^2. Energy comes and goes mc^2 does not change.

When you accelerate the ball, you totally add mass - have you heard of relativistic mass?

It will be minuscule, sure, but very real nonetheless. Relativistic effects don't cease at what is misleadingly called non- relativistic speeds, they just become small enough to be negligible for most practical purposes.

 

[Wiploc]

Adding you can add enrgy to a system without adding mass. Wind up trhe spring of a mechanical clock and you have added energy to the system but no mass.

I hold a baseball in hand. It has potential, kinetic, and nuclear energy. Total energy E = PE + KE + mc^2.
.

I throw the ball in the air adding PE and KE. Total energy is still PE + KE + mc^2. Energy comes and goes mc^2 does not change.

You've got two responses disagreeing with this post. I'm not sure why.

There are other forms of energy than mass. If you heat up the box with the ashes in it, it will have more energy (in the form of heat) without having more mass. If you throw the box of ashes, you'll give it kinetic energy without increasing its mass.

This doesn't change the fact that chemical reactions involve tiny conversions from mass to other forms of energy, or from other forms of energy to mass.

Suppose a hydrogen atom absorbs a photon, thus raising an electron to a higher orbit. Does the atom then weigh more? I'm guessing that it does. The other form of energy is gone, and mass is what remains, so the mass of the atom should be increased by one photon's worth. I don't know this for a fact. I haven't read it anywhere. I'm just thinking it makes sense.

Energy is conserved. If energy comes out of your glass box when the paper burns, then the box contents will have reduced mass. This must be true unless the exiting energy comes from something other than mass. Your hypothetical doesn't mention any other energy source, and we know that burning paper is exothermic.

So the answer is that the chemicals in the box get lighter in proportion to the amount of energy escaping from the box.

 

[bilby]

Adding you can add enrgy to a system without adding mass. Wind up trhe spring of a mechanical clock and you have added energy to the system but no mass.

I hold a baseball in hand. It has potential, kinetic, and nuclear energy. Total energy E = PE + KE + mc^2.
.

I throw the ball in the air adding PE and KE. Total energy is still PE + KE + mc^2. Energy comes and goes mc^2 does not change.

You've got two responses disagreeing with this post. I'm not sure why.

There are other forms of energy than mass. If you heat up the box with the ashes in it, it will have more energy (in the form of heat) without having more mass. If you throw the box of ashes, you'll give it kinetic energy without increasing its mass.

This doesn't change the fact that chemical reactions involve tiny conversions from mass to other forms of energy, or from other forms of energy to mass.

Suppose a hydrogen atom absorbs a photon, thus raising an electron to a higher orbit. Does the atom then weigh more? I'm guessing that it does. The other form of energy is gone, and mass is what remains, so the mass of the atom should be increased by one photon's worth. I don't know this for a fact. I haven't read it anywhere. I'm just thinking it makes sense.

Energy is conserved. If energy comes out of your glass box when the paper burns, then the box contents will have reduced mass. This must be true unless the exiting energy comes from something other than mass. Your hypothetical doesn't mention any other energy source, and we know that burning paper is exothermic.

So the answer is that the chemicals in the box get lighter in proportion to the amount of energy escaping from the box.

You can't give something additional kinetic energy without increasing its mass.