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18
Alt
hough
logarithms were origina
ll
y ured
to
speed multi-
plication and division, they have partIcular
significance
in
scientific and
en
ginee
ring
problems. There is. for example,
a
logarithmIc
relatIonshIp belwtlen
alti
tude
and barometric
pressure. Suppose you
wish
10 use
an
ordinary barometer
as an alIi meIer. Afler measuring the sea level pressure
(30
inches of mercury) you
climb
unlil Ihe barometer
in-
dicates 9.4
inches
of mercury. How hIgh are you? Allhough
Ihe
e~act
relatIonship of
pressure
and
altitude
IS
a function
01 many lactor'$,
a
reasonable
appro~imalion
is
given by:
Press
25000
IlmIl
30
IlmIl
9.4
;;
l1li
£I
30
Altllude
(teet)
•
25,000 In - - -
Pressure
""
Comments
2500
0
.
25000.
30
.
30
9
4
Pressure
a
t altitu
d
e
3.
1
9
1
4
89362
1
60
4
87693
290
12
19233
Altitude
[We SUSpe.c1
thaI
you may be on Mt. Everesl (29.028 feet))
Your
Hp·35
compules trigonometric functions of angles
measured on
degrees
and decimal fractions of a
degree.
E~
ample!
Find
sin
30.5°,
cos
150"
, Ian
_25. 6°
.
Press
So,
Comments
30.5
30
.
5
5075383628
sm 30.5
o
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