Rock Port, Missouri - The First 100% Wind Powered City

[Besoeker]

Originally Posted by LMagic007

Thats ok, you're not expected to understand everything. I never said the physics does not work.

OK. But you said it is not the entire explanation and that my use of it was inappropriate.
Fine. Present details of an alternative explanation that also works.

[spadlet]

Originally Posted by LMagic007

Of course. Energy is ever present in varying forms and states.

Yes, but it the measurement of the change of state and potential for change of state so all energy changes are time dependant. If you do not have time you cannot have an exchange process and thus you do not have energy. So there is no such thing as instantaneous energy because the word 'instantaneous' describes a lack of time. The concept used to measure the rate at which energy is transfered (or change occurs) is called power.

If you have a graph of how a measured quantity of energy changes with time you can differentiate it at any chosen point (find the gradient of the line at that point) to find the magnitude of power. The gradient of the line may change at any instant, depending on the processes involved, so any calculated power value is only true for the moment when it was measured (unless the graph of energy versus time is linear). This results in power being an instantaneous value.

Agreed?

[Besoeker]

Originally Posted by spadlet

Yes, but it the measurement of the change of state and potential for change of state so all energy changes are time dependant. If you do not have time you cannot have an exchange process and thus you do not have energy. So there is no such thing as instantaneous energy because the word 'instantaneous' describes a lack of time. The concept used to measure the rate at which energy is transfered (or change occurs) is called power.

If you have a graph of how a measured quantity of energy changes with time you can differentiate it at any chosen point (find the gradient of the line at that point) to find the magnitude of power. The gradient of the line may change at any instant, depending on the processes involved, so any calculated power value is only true for the moment when it was measured (unless the graph of energy versus time is linear). This results in power being an instantaneous value.

Agreed?

Spot on. I wish I could have explained it with such clarity.

[LMagic007]

Originally Posted by spadlet

Yes, but it the measurement of the change of state and potential for change of state so all energy changes are time dependant. If you do not have time you cannot have an exchange process and thus you do not have energy. So there is no such thing as instantaneous energy because the word 'instantaneous' describes a lack of time. The concept used to measure the rate at which energy is transfered (or change occurs) is called power.

If you have a graph of how a measured quantity of energy changes with time you can differentiate it at any chosen point (find the gradient of the line at that point) to find the magnitude of power. The gradient of the line may change at any instant, depending on the processes involved, so any calculated power value is only true for the moment when it was measured (unless the graph of energy versus time is linear). This results in power being an instantaneous value.

Agreed?

Well the term instantaneous has a number of definitions, including the one you raised among others. Thus depending on what definition one chooses to apply, it could take on different meanings and be applied to different contexts. Application of time measurement is also limited by our ability to measure it.

[Besoeker]

Originally Posted by LMagic007

Well the term instantaneous has a number of definitions,

In the context of energy and power it has only one meaning and that is well-defined. And it is one that you have already, and correctly accepted. See post #118.

I note, in passing, that you still haven't cited an example where the basic physics doesn't work.

[LMagic007]

Originally Posted by Besoeker

In the context of energy and power it has only one meaning and that is well-defined. And it is one that you have already, and correctly accepted. See post #118.

I note, in passing, that you still haven't cited an example where the basic physics doesn't work.

As said before its the application of the law. I accept there are several definitions that can be applied on the context of energy, not just one.

[Besoeker]

Originally Posted by spadlet

If you have a graph of how a measured quantity of energy changes with time you can differentiate it at any chosen point (find the gradient of the line at that point) to find the magnitude of power.

That's true. You can also integrate power
(∫ Pdt) to get energy, of course. In practice, that's normally what's done - you pay for energy in kWh as recorded on an integrating type meter.

[Besoeker]

Originally Posted by LMagic007

As said before its the application of the law. I accept there are several definitions that can be applied on the context of energy, not just one.

Fine. Cite a different one that also works.

[spadlet]

Originally Posted by LMagic007

Well the term instantaneous has a number of definitions, including the one you raised among others. Thus depending on what definition one chooses to apply, it could take on different meanings and be applied to different contexts. Application of time measurement is also limited by our ability to measure it.

Yes, but equally you need to be aware of the fact that the deffinition I have used is the deffinition used by every engineer and scientist that I have ever met when talking about energy and power. If you are going to use a different deffinition of 'instantaneous' in the context of this subject you are going to have to define what you mean in detail otherwise the person you are talking to will think that you mean something different.

'Make sure you say what you mean because people will think you mean what you say' (a French teacher at senior school's favourite phrase)

[Besoeker]

Originally Posted by spadlet

'Make sure you say what you mean because people will think you mean what you say'

I like that.
May I use it?