The opening sentence of section 20.5 on page 547 says:
If we take into account both the transfer of mechanical energy (work) W and the energy transferred thermally Q, the energy law (Eq. 9.1) becomes
To be consistent, it ought to say "energy transferred mechanically" as discussed in a comment attached to item #36, but this item makes a different point.
According to fundamental notions of English grammar, a parenthetical appositive such as (work) means that "work" is synonymous with "transfer of mechanical energy". There is a comment under item #36 that suggests I am misreading this passage, but I reckon a great many other readers will read it the same way.
On page VII promises a "deductive" approach. However, the sentence in question does not deduce the equivalence of work and transfer of mechanical energy. It is more thaumaturgy than deduction. It is proof by parentheses.
The parenthetical appositive not only implies that the two terms are equivalent, it implies that the reader should already know that. However, I have not found any passage in the book that deduces this equivalence.
If there were such a passage, it would just make things worse, insofar as it is bad luck to prove things that aren't true. Work is absolutely _not_ equivalent to the transfer of mechanical energy, nor to the energy transferred mechanically, nor anything similar. This should be obvious from the fact that there is a work/kinetic-energy theorem, not a work/total-energy theorem.
Of course there are ways of restricting attention to special cases where all of the work is mechanical energy transfer and vice versa, as in section 20.1 on page 532 ... but the passage on page 547 does not do this. The issue of non-obvious and inconsistent inheritance of assumptions is discussed in item #187.
Suggestion:
Emphasize the principle of the thing. Talking about «heat» and «work» (with or without euphemisms) will never be the principled approach. Instead it is better to talk about energy and entropy.
In particular, emphasizing "the energy law" equation 9.1 gives students the wrong impression. Replacing it with equation 20.1 gives them a different wrong impression. The emphasis should be elsewhere.
The opening sentence of section 20.5 on page 547 says:
To be consistent, it ought to say "energy transferred mechanically" as discussed in a comment attached to item #36, but this item makes a different point.
According to fundamental notions of English grammar, a parenthetical appositive such as
(work)means that "work" is synonymous with "transfer of mechanical energy". There is a comment under item #36 that suggests I am misreading this passage, but I reckon a great many other readers will read it the same way.On page VII promises a "deductive" approach. However, the sentence in question does not deduce the equivalence of work and transfer of mechanical energy. It is more thaumaturgy than deduction. It is proof by parentheses.
The parenthetical appositive not only implies that the two terms are equivalent, it implies that the reader should already know that. However, I have not found any passage in the book that deduces this equivalence.
If there were such a passage, it would just make things worse, insofar as it is bad luck to prove things that aren't true. Work is absolutely _not_ equivalent to the transfer of mechanical energy, nor to the energy transferred mechanically, nor anything similar. This should be obvious from the fact that there is a work/kinetic-energy theorem, not a work/total-energy theorem.
For further discussion of this point, including a more-or-less unforgettable diagram, see https://www.av8n.com/physics/thermo/state-func.html#sec-e-other-variables
Of course there are ways of restricting attention to special cases where all of the work is mechanical energy transfer and vice versa, as in section 20.1 on page 532 ... but the passage on page 547 does not do this. The issue of non-obvious and inconsistent inheritance of assumptions is discussed in item #187.
Suggestion:
Emphasize the principle of the thing. Talking about «heat» and «work» (with or without euphemisms) will never be the principled approach. Instead it is better to talk about energy and entropy.
In particular, emphasizing "the energy law" equation 9.1 gives students the wrong impression. Replacing it with equation 20.1 gives them a different wrong impression. The emphasis should be elsewhere.