Notation

This list describes several symbols that are commonly used within the body of the book.

$c$ Speed of light in a vacuum inertial frame: $2.99792458 \times 10^{8}\mathrm{m/s} \approx 3 \times 10^{8}\mathrm{m/s}$

$\epsilon$ Efficiency; typically 0 $\le \epsilon \le 1$; unitless

$g$ acceleration due to gravity: 9.8 $\mathrm{m/s}^{2}$ or $\approx 10 \mathrm{m/s}^{2}$

$h$ Planck’s constant: $6.626 \times 10^{-34}$ J $\cdot$ s

$k_{\mathrm{B}}$ Boltzmann’s constant: $1.38 \times 10^{-23}$ J/K

$N_{\mathrm{A}}$ Avogadro’s number: $6.022 \times 10^{23}$ particles per mole

$\Delta Q$ Change in thermal energy, in Joules

$R_{\oplus}$ Radius of Earth: 6,378 km

$R_{\odot}$ Radius of Sun: 695,700 km

$r_{\oplus \odot}$ Earth–Sun distance (1 AU): 149.6 million km

$\sigma$ Stefan-Boltzmann constant: $5.67 \times 10^{-8}\mathrm{W/K/m}^{2}$

$\Delta S$ Change in entropy, in J/K

$\Delta T$ Change in temperature, typically in $^{\circ}\mathrm{C}$ or Kelvin (K)

$\Delta W$ Change in energy—work performed, in Joules