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2. How do we use logarithms? pH level in blood
slope of a beach
speed of wind inside a tornado
magnitude of an earthquake
transport a substance into a human cell
intensity of sound
interest on money
estimate the time of death
3. pH level in blood. The pH of a patient’s blood can be calculated using the Henderson-Hasselbach Formula:
pH = 6.1 + log10 (B/C)
where B is the concentration of bicarbonate, and C is the concentration of carbonic acid.
4. Slope of a beach! The slope, s, of a beach is related to the average diameter, d (in millimeters), of the sand particles on the beach by the formula:
s=0.159 + 0.118log10 d
If the sand is very coarse, the slope of the beach will be steeper than if the sand is fine.
5. Tornado! The speed of the wind, S (in miles per hour), near the center of a tornado is related to the distance the tornado traveled, d (in miles), by the formula:
S = 93 log10 d + 65
6. Earthquake! The Richter scale is used to measure the magnitude, R, of an earthquake of intensity I is given by the formula:
R = log10 I The intensity is a measure of the wave of energy of an earthquake per unit of area.
7. Human Cells! The energy, E (in kilocalories per gram molecule), required to transport a substance from the outside to the inside of a living cell is given by the formula:
E = 1.4(log C2 - log C1) C1 is the concentration of the substance outside the cell C2 is the concentration inside the cell.
8. Sound ! The level of sound, B (in decibels), is related to the intensity of the sound, I (in watts per square cm.), by the formula:
B = 10 log10 (I/I0) I is the intensity of the faintest sound that can be heard by human ears.
9. Natural Logarithms ( ln) Natural logarithms are calculated in base e, which is also called the Euler number, named after Leonard Euler.
10. Interest on $ MONEY! If interest is compounded quarterly, use the formula:
A = P( 1+ r / n ) ^ nt If interest is compounded continuously, use the formula:
A = Pe^ rt
11. Amount of $ after 10 years at 5% interest.
12. Amount of $ after 10 years at 5% interest
13. Time of Death! To estimate the time of death of a human body, a coroner uses Newton’s law of cooling:
Kt = ln(T-S)/(T0-S1) k is a constant, S is the temperature of the surrounding air, t is the time it takes for the body temperature to cool from the time of death.
14. Credits Algebra 2, An Integrated Approach,D.C. Heath and Company
Microsoft clip-art and pictures
Stribling Funeral Home
http://www.animfactory.com/
http://wwwpersonal.engin.umich.edu/~dkyser/weather/pics.htm
Encyclopedia of World Biography, 2nd edition, Diderot and Forbes, 1998