Estimation

Want estimate to be same factor away from upper and lower bounds => use geometric means <x> = (xL xH)¹/2 Approximate geometric means by averaging coefficient and exponents

• Geometric mean c = sqrt(ab) ~ (a+b)/2 x 10 ^(alpha + beta) /2
• 10^(1/2) = sqrt(10) ~ 3

Nucleus: Nucleons are packed together in a nucleus like a liquid (not a gas) so R ~ A^(1/3) rp

Distances:

• 1in = 2.5 cm
• km ~ 0.5 mi
• r_earth ~ 6e6m
• d_cell ~ 10 µm

Volumes:

• 1L = (10 cm)³ (1000L = m³)
• 1L ~ 1quart
• 1 mole gas ~ 20L at STP

Density

• rho_air ~ kg / m³
• rho_W ~ g/cm³ ~ 1000kg/m³ ~ ton/m³
• rho_lead ~ 10kg / m³

Speed:

• 1m/s ~ 2 mph
• vsound ~ 300 m/s

Mass:

• kg ~ 2lbs

Energy:

• 1c ~ 3 J
• C (food calorie) ~ 3e3 J (4e3 J)
• eV ~ 1e-19 J

Power:

• ~10 kWh / day

Gas:

• 1MCF / month (summer) 10 / month (winter)

Water:

• 3 k gallons/month

Chemistry: Hydrocarbons: coal ~ C Methance/natural gas ~ CH4 All else ~ CH2 Reactions: C+O->CO2 / H+0 -> H2O eg: CH2 -> C02 + H20 eg: CH4 -> C02 + 2*H20

• Coal ~ C / NaturalGal ~ Methane ~ CH₄ / All other hydrocarbons/Carbohydrates ~ CH₂

Solar Constante ~ kW / m²

M_sun ~ 10⁵⁷ GeV

Atmosphere:

• STP ~ 10⁵ N/m²
• 10⁴ kg/m² ~ 10 tons / m²

Heat capacity C_w ~ 1cal/g degree-C (Large)