# What is Energy in Thermodynamics ?

1. Jul 24, 2011

### Harisankar

Using Thermodynamics we can measure a certain quantity that is preserved/transferred during a process and we call it energy.
We feel it's existence based on it's effect on other observable quantities(say motion for instance) and we do not "know" energy as itself.Am I right?

So do we energy only as a cause and never as itself?

2. Jul 24, 2011

### aravind.vlb

i think we can define it like that under some lmitations

Last edited by a moderator: Jul 25, 2011
3. Jul 24, 2011

### hubewa

Your first statement is pretty much saying that energy is intangible, which is true.

However, I don't understand the above. Can you please clarify?

4. Jul 24, 2011

### Harisankar

I am really sorry.
I meant to say,"Do we feel energy only as a cause and never as itself?".

Let's say,we feel the effect of heat energy,temperature,we don't feel heat energy itself now,do we?

5. Jul 24, 2011

### hubewa

Not a correct assumption.

When we feel the effect of heat energy, energy is still intangible. No matter how much we want to, it will never become tangible as you seem to suggest so it's impossible to say something like "heat energy itself".

If we do feel the effect of heat energy, well, then we feel the effect of heat energy.

I think that, itself, would be a reasonable analysis. This, rather, is due to the fact is because energy is intangible. You cannot pick up 5J of energy here and there.

If there is something extra that I don't understand, can you please clarify? Thanks.

Last edited: Jul 24, 2011
6. Jul 24, 2011

### Staff: Mentor

No. Making observations and connecting them to each other with math is what physics is about. So that's all that energy is!

7. Jul 24, 2011

### Harisankar

Thank you Aravind,Hubewa and Russ.
You have given me more insight not only to my question but also to the presentation of a question.
So the bottom line is energy is an inherent entity in the universe and it's presence is ascertained only by it's effect on measurable parameters.

8. Jul 24, 2011

### Staff: Mentor

Before you go too far you may want to read other threads by the same name: