 $$\pi$$ pi 3 G Newton's constant $$7 \times 10^{-1} kh^{-1} m^{3} s^{-2}$$ c speed of light $$3 \times 10^{8} m s^{-1}$$ hc h shortcut 200 eV nm $$m_{3}c^{2}$$ electron rest energy 0.5 MeV $$k_{B}$$ Boltzmann's constant $$10^{-4} eV K^{1}$$ $$N_{A}$$ Avogadro's number $$6 \times 10^{23} mol^{-1}$$ R universal gas constant $$k_{B}N_{A}$$ $$8 J mol^{-1} K^{-1}$$ e electron charge $$1.6 \times 10^{-19} C$$ $$\frac{e^{2}}{4 \pi \epsilon _{0}}$$ electrostatic combination $$2.3 \times 10^{-28} kg m^{3} s^{-2}$$ $$\frac{e^{2}}{4 \pi \epsilon_{0}} /hc$$ fine-structure constant $$\alpha$$ $$0.7 \times 10^{-2}$$ $$\sigma$$ Stefan-Boltzmann constant $$6 \times 10^{-8} W m^{-2} K^{-4}$$ $$M_{Sun}$$ solar mass $$2 \times 10^{30} kg$$ $$m_{Earth}$$ Earth's mass $$6 \times 10^{24} kg$$ $$R_{Earth}$$ Earth's radius $$6 \times 10^{6} m$$ AU Earth-Sun distance $$1.5 \times 10^{11} m$$ $$\Theta _{Moon or Sun}$$ angular diameter of Moon or Sun $$10^{-2} rad$$ day length of a day $$10^{5} s$$ year length of a year $$\pi \times 10^{7} s$$ $$t_{0}$$ age of the universe $$1.4 \times 10^{10} yr$$ F solar constant $$1.3 kW m^{-2}$$ $$p_{0}$$ atmospheric pressure at sea level $$10^{5} Pa$$ $$\rho _{air}$$ air density $$1 kg m^{-3}$$ $$\rho _{rock}$$ rock density $$2.5 g cm^{-3}$$ $$L_{vap}^{water}$$ heat of vaporization of water $$2 MJ kg^{-1}$$ $$\gamma_{water}$$ surface tension of water $$7 \times 10^{-2} N m^{-1}$$ $$P_{basal}$$ human basal metabolic rate $$100 W$$ $$a_{0}$$ Bohr radius 0.5 Å a typical interatomic spacing 3 Å $$E_{bond}$$ typical bond energy 4 eV $$\varepsilon_{fat}$$ combustion energy density $$9 kcal g^{-1}$$ $$v_{air}$$ kinematic viscosity of air $$1.5 \times 10^{-5} m^{2} s^{-1}$$ $$v_{water}$$ kinematic viscosity of water $$10^{-6} m^{2} s^{-1}$$ $$K_{air}$$ thermal conduvtivity of air $$2 \times 10^{-2} W m^{-1} K^{-1}$$ K ...of nonmetallic solids/liquids $$2 W m^{-1} K^{-1}$$ $$K_{metal}$$ ...of metals $$2 \times 10^{2} W m^{-1} K^{-1}$$ $$c_{p}^{air}$$ specific heat of air $$1 J g^{-1} K^{-1}$$ $$c_{p}$$ ...of solids/liquids $$25 J mol^{-1} K^{-1}$$