JohnDenker
commented
8 years ago By way of contrast, here's a happy, positive example. The book discusses the ideal gas law, without so much as mentioning Boyle's law, Charles's law, Avogadro's law, or any of the other low-value restricted corollaries. This is as it should be, because anybody with the slightest understanding of algebra can derive the corollaries on the fly, if/whenever needed.
In the marketing materials for the book, and in the very title, it promises to emphasize concepts. On page VII it promises to prioritize concepts over terminology.
However, there are more than a few places where there is an emphasis on terminology that works against the ideas. Sometimes the terminology is non-standard, for no good reason. Here are some examples:
branch ruleis introduced in section 31.3 on page 816. The index does not mention any other occurrences of the term. (See #181 for a catalog of index-related issues.) This is a highly nonstandard term, and if I hadn't just looked it up, I would have no idea what it meant. If you google the term, you find references to the tax code. If you google «"the branch rule" physics» you get vastly fewer results, but still nothing useful in this context. I asked some physics professors, and they had no idea. When I said it was in the context of electric circuits, they guessed that it had something to do with voltages and/or currents in a series-connected circuit, but they couldn't be specific.energy lawis presented as equation 9.1 in section 9.5 on page 213. This is highly non-standard terminology. If you google the term, you get references to the legal system, not physics. If you google «"energy law" physics» you find that everybody else refers to it as simply conservation of energy. Calling it the "energy law" is less descriptive. It is unhelpful in pedagogical terms, in practical terms, and in every other way.Furthermore, it must be emphasized that equation 9.1 is not a correct or complete statement of conservation of energy. It is a highly restricted corollary thereof.
Laplace's law. I asked some physics professors about this, and they had no idea. Although this is somewhat standard terminology, in the sense that you can google it and find out what it means, it is not the sort of thing I would ask students to remember. There are multiple versions of the law, and it is not humanly possible to keep them all straight. The principled approach would be to understand PVW and apply it when needed, as discussed in item #150.atomas discussed in item #178.equation of motionnamely equation 8.7, which appears in section 8.7 on page 188, and emphasized in the chapter summary (aka «glossary») on page 201. In the real world, there are many, many equations of motion. The idea that equation 8.7 is «the» equation of motion is just silly.Furthermore, the idea that (a=F/m) would be its own law with its own name, separate from Newton's second law, is the opposite of the principled approach. It is the epitome of equation-hunting. It is what we expect of students who don't understand algebra (which is very odd, since the book requires calculus elsewhere). Specifically, it reminds me of the morbidly amusing story about the three laws of electronics: https://www.av8n.com/physics/math-intro.htm#sec-electronics
absolute zerowhich is defined in section 20.2 on page 536. The definition is inconsistent with the definition of temperature given elsewhere in the book. Also the definition asserts without proof (indeed without evidence) that the entropy goes to zero at T=0, as discussed in item #182.entropy gradientwhich is introduced in section 21.2 on page 567 and emphasized in the chapter summary (aka «glossary») on page 592. That is a highly nonstandard term. Nobody calls it that; there is an obvious standard term that could be used instead. Furthermore, «entropy gradient» is a misnomer insofar as it's not a gradient; really it's just a directional derivative. In contrast, in a multi-dimensional space such as this, any _gradient_ is a vector, not a scalar. The real entropy gradient can be written as plain dS or equivalently ∇S. Expecting students to memorize a bogus definition of «entropy gradient» seems like the opposite of the principled approach. It seems like terminology running roughshod over the concepts.source energyas discussed in item #35. First of all, it is nonstandard terminology, and secondly it refers to something that doesn't exist in the real world. On page VII the book promises "ideas before names" but here we have a name with no viable idea behind it.