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Example: Roy Lawbreski's swimming pool is 3.5 meters deep under
the diving board. What is the pressure at that depth. (Atmospheric
pressure is 1.01 x10° N/m?, G = 9.81 m/second?, and the density
of water is 1,000 kg/m3).
Keys:
Display:
Description:
I ?value
Prompts for I.
1.01 @(E]5
D?value
Stores I, prompts for
D.
1000
G?value
Stores D, prompts for
G.
9.81
H?value
Stores G, prompts for
H.
35
P=135,3350088
Stores H, calculates
pressure (N/m?2).
Radioactive Decay
The equation for radioactive decay of a substance is:
"KXT=LN(N+I)>
where
I =
the amount or activity of the substance at T = 0.
K =
the rate constant for the decay, characteristic of the
particular substance. Variables T and K must use the
same time units.
N =
the amount of the substance or activity at time T.
T =
elapsed time.
Example: Carbon-14 Dating. Part 1: Wood on the outer surface of
a giant sequoia tree exchanges carbon with its environment. The ra-
dioactivity of this wood is 15.3 counts per minute per gram of carbon.
A sample of wood from the center of the tree yields 10.9 counts per
minute per gram of carbon. The rate constant for the radioactive form
of carbon, 14C, is 1.20 x 10~* year~!. How old is the tree?
7: The Equation Library
103
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