Could these statments define energy?

  • #1
A.Energy is a concept that quantifies the amount of work previously done on an object as well as the amount of work than an object can perform (both of which are equal). B. Energy must always be transferred by the means of a physical force. C. All forces cause work from a macro perspective viewpoint. Forces can only be exerted by objects that have had work preformed on them previously.

If the total energy in the whole universe was and will be constant through all time then does that mean that there is a fixed center of mass of the universe?
 
Last edited by a moderator:

Answers and Replies

  • #2
nasu
Gold Member
3,772
429
Fixed in respect to what?
 
  • #3
To change the center of mass of a system of objects( I this case the whole universe) there must be an input or out put of energy, therefore is it true that the center of mass of the universe has been and will be at the same position on a 3 demensional plane for all of time.
 
  • #4
nasu
Gold Member
3,772
429
No, to have the center of mass moving with constant speed you don't need any input of anything.
But before even talking about motion and rest you need a reference frame.
 
  • #5
Drakkith
Staff Emeritus
Science Advisor
21,105
4,933
To change the center of mass of a system of objects( I this case the whole universe) there must be an input or out put of energy, therefore is it true that the center of mass of the universe has been and will be at the same position on a 3 demensional plane for all of time.
No, the universe has no known center of mass. It also has no known center or edge.
 
  • #6
Ok the center of mass part of the statments is incorrect, but what about the energy statments?
 
  • #7
nasu
Gold Member
3,772
429
What energy statements?
 
  • #8
At the top of the page A B C
 
  • #9
nasu
Gold Member
3,772
429
As heat is a form of energy transfer that correspond to no macroscopic work, your 2 and 3 seem to be contradictory.

What are trying to do, anyway? Make e new "theory" of energy?
 
  • #10
42
3
The amount of work done is the change in kinetic energy of the object the work is being done on. That is not necessarily equal to the amount of work the object can do, because the change in energy is not always equal to the total energy. Correct me if I'm wrong. Work=Force times displacement caused while the force was exerted. The energy is not the maximum amount of work an object can do, because doing work requires changing the energy by adding an external force (an object in rest cannot just suddenly do work), not using the energy.
 
Last edited:
  • #11
To respond to Nasu, the transfer of heat energy requires the collision of particles, thus work must have been preformed to cause a higher average kinetic energy in the particles until they moved and collided with another to transfer kinetic energy to the other's particles.
 
  • #12
nasu
Gold Member
3,772
429
But you say "All forces cause work from a macro perspective viewpoint".
Do you call the work done when two molecules collide a work "from a macro perspective"?
Then what is not "macro" in your conception?
 
  • #13
All matter had to have work applied on it to simply exist( movement of all subatomic particles into position) I am simply saying defining the total energy in an object at a particular instance of time in part A.
 
  • #14
42
3
As heat is a form of energy transfer that correspond to no macroscopic work, your 2 and 3 seem to be contradictory.

What are trying to do, anyway? Make e new "theory" of energy?
Heat is partially work, though, right? Heat is random vibration, but some of the vibration will be in the direction of the force exerted, so by heating something up, work is being exerted (the collisions of the particles exert a force on each particle). Sorry if I'm wrong.
 
  • #15
nasu
Gold Member
3,772
429
Now you are even more confusing. So what happens if there is no work done on some piece of matter? It does not exist anymore?

Maybe you start by saying what are you trying to do? You think you have a new definition of energy? Or something else maybe?

Edit.
Actually my message was for the OP but you posted in the meantime.
 
  • #16
42
3
Now you are even more confusing. So what happens if there is no work done on some piece of matter? It does not exist anymore?

Maybe you start by saying what are you trying to do? You think you have a new definition of energy? Or something else maybe?
No, it is just at absolute zero, which is impossible. Either that or it is in a perfect vacuum, which is impossible, at least in the perspective of the universe.
 
  • #17
nasu
Gold Member
3,772
429
Heat is partially work, though, right? Heat is random vibration, but some of the vibration will be in the direction of the force exerted, so by heating something up, work is being exerted (the collisions of the particles exert a force on each particle). Sorry if I'm wrong.
No, heat is heat and work is work. See the second law of thermodynamics.
You can have heat transfer without any macroscopic work. See isochoric transformation of a gas, for example.
 
  • #18
nasu
Gold Member
3,772
429
No, it is just at absolute zero, which is impossible. Either that or it is in a perfect vacuum, which is impossible.
You are confused about the concepts of work or maybe you used the term in an unusual way.
I cannot make sense of this statement.
 
  • #19
42
3
In order for there to be no heat transfer by convection or conduction, you must have the object in a perfect vacuum or be at absolute zero temperature (meaning no vibrations; this would also remove heat loss by radiation). It was because of these statements:
All matter had to have work applied on it to simply exist( movement of all subatomic particles into position) I am simply saying defining the total energy in an object at a particular instance of time in part A.
So what happens if there is no work done on some piece of matter? It does not exist anymore?
Also: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heat.html
 
  • #20
nasu
Gold Member
3,772
429
But I don't see how the absence of heat transfer by convection or any other mechanism is relevant to the main discussion. Assuming that there is a main discussion. :)
 
  • #21
42
3
Yeah, it got a little off topic with everyone arguing.
 
  • #22
Matter as we know it(electrons, protons, neutrons) do not exist unless work was previously exerted on the constituent particles to bring them together? If this is true then we can use the oversimplified expression E=mc^2 to quantify the amount of work that was done simply in the sense of assembling the mater into something we can recognize.

By macro perspective viewpoint I mean taking all objects in the universe into consideration when ever an action takes place. Not from the viewpoint of a singular object.

To get back on topic do A,B,C define energy?
 
Last edited by a moderator:
  • #23
nasu
Gold Member
3,772
429
So you don't see the contradiction between B and C, when heat transfer is considered?
 
  • #24
So let be explain B anC better
 
  • #25
nasu
Gold Member
3,772
429
What are you goals, anyway?
Are you dissatisfied with the standard definitions of various forms of energy?
 

Related Threads on Could these statments define energy?

Replies
4
Views
2K
  • Last Post
2
Replies
31
Views
4K
  • Last Post
Replies
18
Views
2K
Replies
17
Views
2K
Replies
1
Views
656
Replies
3
Views
1K
Replies
13
Views
8K
Replies
37
Views
5K
Replies
8
Views
2K
Replies
2
Views
2K
Top