The entropy of systems

No work is done without an effect that can be observed. Holding the book is a force applied with no work being done-so "a" is the right answer. Where does energy enter the project?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />No work is done without an effect that can be observed. Holding the book is a force applied with no work being done-so "a" is the right answer. Where does energy enter the project?
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The effect CAN be observed. The effect is called "weight". You can see it by placing a weight scale under the book. The work being done: The book is trying to move through the table. The pressure caused by the weight of the book is distributed through the legs and to the ground. The atoms react to this extra weight (this is only one variable which affects the energy state of the atoms in that table. others are: temperature, time...)

Jim: "No work is done without an effect that can be observed"

GD: A force implies a <i>cause</i> and an <i>effect</i>, Work is part of this process.

Jim, are you saying that in example b) there is no work either ?

Jim: Here is a definition of work which says it exactly like you:

"In physics, work is the amount of energy transferred by a force.

Like energy, it is a scalar quantity, with SI units of joules. Heat conduction is not considered to be a form of work, since there is no macroscopically measurable force, only microscopic forces occurring in atomic collisions. In the 1830s, the French mathematician Gaspard-Gustave Coriolis coined the term work for the product of force and distance. "

I say this is wrong, since all forces in nature originate from matter itself. Energy transfer within matter will cause forces. Therefore heat transfer will in fact do "work" (+ energy loss).

GD, It eems to me work is just one of many effects that are observed when matter and energy interact. Work is an engineering concept and should be understood to be part of a value system rather than some more profound effect like heat or light. It seems to me all these concepts are misused without any notice by anyone which leads to confusion. For example, heat is not energy but everyone uses these concepts as if the words were interchangable. Heat only exists in matter and energy can exist without matter. Thats just one of many ways concepts get misused.

Jim,

Is the term "work" used wrongly in chemistry then ?:

" The principle of maximum work "

"In the history of science, the principle of maximum work was a postulate concerning the relationship between chemical reactions, heat evolution, and the potential work produced there from. The principle was developed in approximate form in 1875 by French chemist Marcellin Berthelot, in the field of thermochemistry, and then later in 1876 by American mathematical physicist Willard Gibbs, in the field of thermodynamics, in a more accurate form. Berthelot's version was essentially: "every pure chemical reaction is accompanied by evolution of heat." (and that this yields the maximum amount of work). The effects of irreversibility, however, showed this version to be incorrect. This was rectified, in thermodynamics, by incorporating the concept of entropy."

" The principle of maximum work "

" essentially: "every pure chemical reaction is accompanied by evolution of heat." (and that this yields the maximum amount of work). The effects of irreversibility, however, <i>showed this version to be incorrect</i>. This was rectified, in thermodynamics, by incorporating the concept of entropy."

- There seems to be a mistake: the text should mention as this being correct. Work is accompanied by energy loss in the form of heat.

- basically: the maximum amount of work decreases with time. This is why rivers do not flow uphill.
Jim, you probably think I am mixing chemistry and physics. To me this is all about energy and the atom, therefore the same subject.