In yesterday’s Get a Grip, Drew asks a reasonable question in response to my pedantry about the use of terminology:

So when is the word ‘suck’ used appropriately (trying not to sound dirty, here)? Can’t there be a colloquial usage if we know what it actually means?

Used appropriately? Probably never, or rarely. And I have to admit, I can’t think of a situation (on short notice) where this conceptual mistake would cause a problem. We scientists can be rather anal meticulous about terminology, and there is a reason for it. Sloppy terminology might lead one to construct a flawed model of how things actually work, much like when one uses an analogy — there are always circumstances under which the explanation fails to hold. By using the proper terminology, the model is better and there are fewer circumstances under which it will fail.

This is not the only example of the sloppy language phenomenon. Others include heat and deceleration. Heat is probably the worst, and in no small part because physicists are sloppy in using it. To begin with, we present it in two different ways: as a process, by which energy is transferred because of a temperature difference, and also as the energy itself that is transferred. A problem arises when we use the two interchangeably. We then talk of heat flow or heat transfer, which is awkward if we are referring to a process. Beyond that, this reinforces the notion that heat (or, in general, energy) is a substance, as if you could have a little pile of heat somewhere, and heat transfer then invokes the image of pouring this substance from one container to another. The huge drawback here is that the misconception sidesteps thinking about the physical processes of conduction, convection and radiation. Heat (like work) isn’t something in a container, but we reinforce this error by using the term “heat capacity,” which tends to encourage this idea. All of this without even getting into the commonly-held misconception that infrared light and heat are the same thing.

Deceleration is an unnecessary term in physics, because acceleration is a vector, which just makes it a special case where the acceleration and velocity are in opposite directions. But some students have a hard time with the concept of vectors, and decoupling the terminology probably isn’t helpful, especially when you get into circular motion, where there’s an acceleration that doesn’t change the speed at all.

As I said at the outset, I can’t think of the pathway where using “suck” leads one onto the moors of misconception and into the bog of bafflement (not to mention possibly going over the cliffs of insanity), but I’m sure there is one. Because if there is one thing I learned while teaching, it’s not to underestimate the ways in which students will misunderstand concepts.

(edit: I don’t mean this last remark in a bad way — it’s not meant to disparage students. The issue is that if a teacher erroneously assume s/he understands what a student’s misconception is, the misdiagnosis is going to make it harder to fix the problem.)