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What is Energy


Lightmeow
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Hello all,

 

Question, what is energy? My science teacher vaguely defined it as the ability to do work. What does that mean? Light I believe is energy, but it doesn't do anything like work?

 

This is a really hard question to explain, so sorry for my not explaining it enough.

 

Hope you can help, and thanks for reading...

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Hello all,

 

Question, what is energy? My science teacher vaguely defined it as the ability to do work. What does that mean? Light I believe is energy, but it doesn't do anything like work?

 

This is a really hard question to explain, so sorry for my not explaining it enough.

 

Hope you can help, and thanks for reading...

Light has energy, it isn't energy. And light has the ability to do work. Just consider anything that has a solar panel.

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I think energy transforms from one form to another, its defined as the potential to do work.....which takes alot of forms, for example you could release light, heat or electricity....they would all be forms of energy.

 

There are various base units for different forms of matter that equate to energy, mass via breaking protons and neutrons apart in an unstable isotope (super heavy metals are usually very unstable and release radiation by just reacting with the natural atmosphere) are one of the more complex examples of energy ...... from mass.

 

You can much more easily use energy from something like zinc and sodium or potassium for example.

 

I think the standard unit of energy is joules but depending on the the work being done.

 

 

To make it clear, energy could be defined as the process that physical objects use when they transform from one form to another, such as electricity into a light (bulb). The energy of the system can be defined in terms of the potential light you get get, aswell as heat.

 

A simple analogy would be work in real life, like building a house. You have to work (use energy) to build the house (create light). You would say that work done by your hands in laying the bricks and mixing the cement is the same as the electrons moving through a wire to a filament in a bulb. The source of energy is the food your body turns into calories which is the same as having a source of electricity such as a battery. You can build the house or light the bulb for as long as the food lasts or electricity lasts in a battery. The energy then essentially equates to the amount of food because your potential to build the house will only last as long as you can feed your body to keep working. As you can see the potential work equates directly to the amount of food. Therefor we break the food down into say 10 days worth of food and say we have 10 days worth of energy (potential work).

 

 

Strangely enough calories are actually units of joules which is a form of energy.

Edited by DevilSolution
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"To make it clear, energy could be defined as the process that physical objects use when they transform from one form to another, such as electricity into a light (bulb). "

That doesn't make it clear.

You could define it that way, but nobody does, because it wouldn't fit with all the other definitions.

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My science teacher vaguely defined it as the ability to do work.

Right, that is the thermodynamic definition of energy. Energy is the property of "stuff" that allows for change or movement.

 

Remember that energy is a property of your physical configuration and not something that can exist independently. So light has the property of carrying energy, but light is not "pure energy".

 

One cannot really answer your question better than this. Energy is a number we can calculate given some physical configuration and this number seems to be useful.

 

The conservation of energy is a consequence of the physics not changing in time. Mathematically this is to do with the symmetries of our theories.

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Slightly different approach: as physicists working on steam engines observed that work, unburnt fuel, later electricity, and others, could convert into heat, and always into the same amount of heat, they found useful to call each one a "form of energy", with the sum of all forms being conserved.

 

Then they added a second law telling that only a fraction of heat can be harvested as work, the rest staying as heat.


Remember that energy is a property of your physical configuration and not something that can exist independently. So light has the property of carrying energy, but light is not "pure energy".

Up to now I've found convenient to consider light as energy. Or maybe it's a matter of wording: energy is located where light is, not at the emitting nor receiving objects, during the propagation of light. During propagation, energy is stored where there is no object, in vacuum.

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"To make it clear, energy could be defined as the process that physical objects use when they transform from one form to another, such as electricity into a light (bulb). "

That doesn't make it clear.

You could define it that way, but nobody does, because it wouldn't fit with all the other definitions.

 

So, e = mc^2 is wrong then? Because thats the process of transforming one physic object (mass) into heat and others (energy).

 

You sure no one else uses that definition?

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Up to now I've found convenient to consider light as energy. Or maybe it's a matter of wording: energy is located where light is, not at the emitting nor receiving objects, during the propagation of light. During propagation, energy is stored where there is no object, in vacuum.

 

Classically, electromagnetic waves carry energy. Energy is a property of "stuff" and in this case it is a property if the electromagnetic fields in question.

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So, e = mc^2 is wrong then? Because thats the process of transforming one physic object (mass) into heat and others (energy).

 

You sure no one else uses that definition?

Einstein's Relativity equation, E=MC^2 is not a process of transforming matter into energy or energy into matter. It is an equivalence theorem meaning that mass has energy and energy has mass.

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Einstein's Relativity equation, E=MC^2 is not a process of transforming matter into energy or energy into matter. It is an equivalence theorem meaning that mass has energy and energy has mass.

 

The latter part of the statement is not true. The equation says that when totaling up the amount of energy in a system, one must include mass as one form of the energy, i.e. mass is a form of energy, and the amount is given by mc2. The equation does not say that energy has mass. To say that requires a new definition of mass that is different from the mass used in other equation, and it does not follow from the way the equation was derived.

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The latter part of the statement is not true. The equation says that when totaling up the amount of energy in a system, one must include mass as one form of the energy, i.e. mass is a form of energy, and the amount is given by mc2. The equation does not say that energy has mass. To say that requires a new definition of mass that is different from the mass used in other equation, and it does not follow from the way the equation was derived.

I stand corrected, well said.

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  • 3 weeks later...

Energy is a Mechanism of Informtion. All Things have a Mechanism to transfer information, and information itself is wave form. And so energy itself is also wave forms...

 

I would like to know this... What is The First Wave to come into existence? All things have the same First Wave...

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ajb, on 10 Dec 2013 - 10:14 AM, said:

Classically, electromagnetic waves carry energy. Energy is a property of "stuff" and in this case it is a property if the electromagnetic fields in question.

Would it be right to say that a photon is the simplest form of an energetic system? If this is true, isn't it why many people consider light to be energy itself because that's the most fundamental system that can exist possessing it?.

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Would it be right to say that a photon is the simplest form of an energetic system? If this is true, isn't it why many people consider light to be energy itself because that's the most fundamental system that can exist possessing it?.

 

Why is a photon simpler than an electron or a neutrino?

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Would it be right to say that a photon is the simplest form of an energetic system? If this is true, isn't it why many people consider light to be energy itself because that's the most fundamental system that can exist possessing it?.

What would we really mean by "simplest"?

 

I guess people sometimes think of light as "pure energy" as photons are massless. But photons do have other properties such as spin and momentum. So, why not think of photons as "pure momentum" or "pure spin"?

Energy is a Mechanism of Informtion.

What do you mean by this?

 

Are you talking about Shannon's information and the relations (maybe just formally) with statistical mechanics and in particular entropy?

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ajb, on 02 Jan 2014 - 11:28 AM, said:ajb, on 02 Jan 2014 - 11:28 AM, said:

What would we really mean by "simplest"?

 

I guess people sometimes think of light as "pure energy" as photons are massless. But photons do have other properties such as spin and momentum. So, why not think of photons as "pure momentum" or "pure spin"?

I meant simplest as in with the least components but I'm wrong any way as Swansont pointed out. I think you hit it on the head why people probably think this, it's because they are massless.

Edited by StringJunky
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Actually the term energy coins two different meanings

1.capacity to do work..

2.it can be of solar energy ,mechanical energy ,magnetic ......

2->the amount of internal power that can be gain by having the solar power in to a substance can be treated as the increase of solar energy in the substance..in this case energy refers to the power

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Energy is anything that can hold, store, or otherwise represent any type of information. Energy is matter, light, electricity, and all other types of electromagnetic wave functions. Elizsia said something very similar, of not exactly this. To answer elizsias questions, there doesn't have to be any first wave. There is no reason all waves have to have a begging point from which they all stem from. Antimatter is the exception to this definition of energy however, because although it is energy, it is technically a bit different from regular matter and energy. This reply was quite difficult for me to word so correct me if I was wrong at all, or if I worded something in a bad way.

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Hello all,

 

Question, what is energy? My science teacher vaguely defined it as the ability to do work. What does that mean? Light I believe is energy, but it doesn't do anything like work?

 

This is a really hard question to explain, so sorry for my not explaining it enough.

 

Hope you can help, and thanks for reading...

consider taking your teacher's words as true because this will be the best way to understand your class. to help you out with light being energy...

 

light is made of little packages of momentum or "push". in fact a photon is the smallest amount of "push" that you can make. that is why light doesn't seem to do much work at all.

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light is made of little packages of momentum ...

To state this better you mean that photon has a property that we call momentum and a property that we call energy. You should not think of a photon as pure momentum or pure energy.

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What would we really mean by "simplest"?

 

The quanta of electromagnetism:

 

The inertial mass is independent of minkowski coordinate system.

It combines in superposition; it is spin 1.

Its intrinsic mass is rational in any system of measurement.

The phase velocity and group velocity of a free particle are equal independent of the direction of measurement.

The photon is it's own antiparticle.

Its baryon number is zero.

Its isospin is zero.

It has no other family members; it does not exist as a resonance of multiple family members.

It is colorless.

It's electric and magnetic charge are zero.

It has multiple classical gauge invariances-- 3 or 4 I think.

It has zero dipole moment.

 

What other particle is this featureless?

Would it be right to say that a photon is the simplest form of an energetic system? If this is true, isn't it why many people consider light to be energy itself because that's the most fundamental system that can exist possessing it?.

Note that photons have more than just properties of energy. See particle properties here http://en.wikipedia.org/wiki/List_of_particles

 

So they are not just "pure energy"--whatever that could mean.

 

2nd: "Energy" is a highly overrated physical quantity. It is not conserved--even in Newtonian physics.

 

3rd: You speak of "a photon". What photon? As particles they are indistinguishable, and even how many photons are existent in a system is an uncertainty.

Edited by decraig
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When we say that Energy is the capacity to do work. It makes it sound like energy is a theoretical idea.... Not a natural phenomena...

 

I understand it as the capacity to do work.

 

What is this entity we call energy? What is it really?

Edited by AndresKiani
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