Greenwood press

EXPONENTIAL DECAY
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between the coffee temperature and the room temperature. The formula for the
coffee temperature after 
t minutes is T = T
r
+ (T
o
− T
r
)e
−kt
, where 
T
o
is the
initial temperature of the coffee, 
T
r
is the room temperature, and 
k is a constant
depending on the type of cup. Hence cooling is an exponential decay situation.
(See Asymptote.)
Medical examiners use a version of Newton’s law of cooling to determine the
time of death based on the temperature of a corpse and ambient temperature at
the murder scene.
online sources for further exploration
Journal of Online Mathematics and Its Applications

Carbon dating


Cooling



Nuclear medicine 

Radioactive decay


The RC circuit 

Used car prices


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EXPONENTIAL GROWTH
Exponential growth situations are based on repeated multiplication. A classic
example was the growth of the rabbit population in Australia. English wild rab-
bits are not native to Australia, but were introduced by Thomas Austin of Win-
chelsea, Victoria, onto his property in 1859. Australia provided an ideal environ-
ment for the rabbits, with plenty of food and no predators, so the population grew
rapidly. By 1910, rabbits had become a plague, driving out many of the native
species across Australia. They destroyed farming areas, caused severe erosion,