36
Units of Scientific Measurements
SOLUTION:
w , •
I™
mi \ l^ an
ft \ / , in\ / cm\ / 1 hr \ / 1 min\
Velocity = 20 — 5280 — 12 r 2.54— ——— —
V hr/ \
mi/ \ ft/\
in/\60 mm/ \60 sec/
= 894^sec
PROBLEM:
Find the conversion factor F by which you would convert Ibs/ff to kg/m
3 .
SOLUTION:
^-(—
m
3 ~ I ft
3
(
lbs \ UA*A *\ / !
k 8\ / 1 ft\
3 / lin.
= IfFJ [I
454 ibj iToWiJ lillj 12^
F = 16.03
TEMPERATURE
Three different scales are in common use for measurements of temperature:
the Celsius scale (expressed in degrees Celsius, or °C), the Fahrenheit scale
(expressed in degrees Fahrenheit, or °F), and the Kelvin scale (expressed in
kelvins, or K). The Fahrenheit scale is commonly used in daily life and in
engineering work. The Celsius scale is used in scientific work and is coming into
common usage in daily life in English-speaking countries. The Kelvin scale
(also called the absolute scale) is the SI choice for temperature measurements,
and it is widely used in scientific work.
Table 4-3 compares the three scales. Each scale has a different zero point.
The size of the unit is the same for the Celsius and Kelvin scales, but it is
TABLE 4-3
The Three Temperature Scales
Reference point
Boiling point of water
Freezing point of water
Difference (FP to BP)
F
212°
32°
180°
Scale
C
100°
0°
100°
K
373.2
273.2
100