APES Formulas and Math Concepts

Percent Change

Ending amount - starting amount X  100

           Starting amount

Productivity

Gross Primary Production - Cellular Respiration = Net Primary Productivity

Trophic Levels

90% loss of energy/biomass as you go up a trophic level

Population Density

Population   =   Population Density

     Area

Birth Rate

         Births____ =  Birth Rate 

Total Population

Death Rate

_____Deaths_____    =   Death Rate

Total Population                               

Population Growth Rate (Crude Growth)

  Births - Deaths   = Crude Growth Rate (r)

Total Population

Population Growth Rate (Growth Rate w/ Migration)

(Births + Immigration) – (Deaths + Emigration)

Total Population

=

Growth Rate (r) with migration factored

Rule of 70 (Used to find Doubling Time of a population)

70%             (r is growth rate in a percentage)

  r

Density

Mass/volume

Metric System Conversions

Giga (G)  109

Mega (M) 106

Kilo (k) 103

Basic Unit (gram g, liter l, meter m, Joule J, Watt W)

Centi (c) 10-2

milli (m) 10-3

micro or micron (µ) 10-6

nano (n) 10-9

pico (p) 10-12

pH Scale

1 # decrease on scale = 10x H⁺ (acidity)

Its exponential and logarithmic.

ex.) A solution with pH of 2 has 1000 times more H⁺ ions than a solution with a pH of 5.

This is because 5-2 = 3.  So three tens multiplied = 10 x 10 x 10 = 1000

 

Energy

Watts and hours combine in energy math. Usually, we combine kW and h to get kWh. Your electricity bill is in kWh.

Example: A TV uses 200 watts and runs for 6 hours. This is 1200Wh OR 1.2kWh.

Half Life

Nt​=N0​×(21​)t1/2​t​