Hey, sorry for having no Sunday Function yesterday. Life and travel conspired in such a way as to prevent it. Well, there’s always next week! But hey, at we have a post for today.

In physics, as in all mathematical disciplines, we have a lot of need for equations. Those equations contain letters which represent various numbers or quantities. We have plenty to choose from, with the letters both Latin-derived and Greek-derived. Even so that’s only a couple dozen letters, and there’s a *lot* of things to represent. E might be energy, or electric field. C might be the speed of light, or just a generic integration constant. But I bet the worst offender if terms of being used for different things is the nondescript and unassuming letter k. Offhand:

k – the spring constant in Hooke’s Law.

k_{b} – Boltzmann’s constant

k – the Coulomb force constant, k = 1/(4 π ε_{0})

k – another name for the z direction

k – (with a hat over it), the unit vector in the z direction

K – Kelvin degrees

K – the metric prefix for kilo

**k** – the wave vector

k – the wavenumber (the magnitude of the above wave vector)

k – a generic (usually integer) constant, after m, n, and l are already used.

k – a Latin index running over 1,2, and 3 for tensor notation in electrodynamics, general relativity and other fields.

K – kinetic energy

K_{J} – the Josephson constant

K – one of several variants of K mesons in particle physics

Are the more? Almost certainly, this is just what I can remember in 5 minutes of thinking. Maybe it’s time for some new letters.