HP 48g Graphing Calculator - Manual (Page 128)

10
Working with Temperature Units
The HP 48 lets you work with temperature units the same ways you
work with other units—except you must recognize and anticipate the
difference between temperature level and temperature difference.
For example, a temperature level of 0 °C means “freezing,” but a
temperature difference of 0 °C means “no change.”
When °C or °F represents a temperature level, then the temperature
is a unit with an additive constant: 0 °C = 273.15 K, and
0 °F = 459.67 “R. But when “C or °F represents a temperature
difference, then the temperature is a unit with no additive constant:
1 “C = 1 K, and 1 °F = 1 °R.
Converting Temperature Units
Conversions between the four temperature scales (K, °C, °F, and
°R) involve additive constants as well as multiplicative factors. The
additive constants are included in a conversion when the temperature
units reflect actual temperature levels, and are ignored when the
temperature units reflect temperature differences:
■ Pure temperature units (levels). If both unit expressions consist of a
single, unprefixed temperature unit with no exponent, the UNITS
Catalog menu or CONVERT performs an absolute temperature
scale conversion, which includes the additive constants.
B Combined temperature units (differences). If either unit expression
includes a prefix, an exponent, or any unit other than a temperature
unit, CONVERT performs a relative temperature unit conversion,
which ignores the additive constants.
Example:
Convert = C t o = F .
fr^fUNITS) [NXTl
25 “ C a)
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1 ^ '
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1 BHMBEMBBaHBB M—¡1
10-10 Unit Objects