|
Description
|
|
|
•
|
Energy has the dimension mass length squared per time squared. The SI unit of energy is the joule, which is defined as a kilogram meter squared per second squared.
|
|
•
|
Work and heat are physical quantities with the same dimension as energy.
|
|
•
|
Maple knows the units of energy listed in the following table. The context IT indicates International Table.
|
|
Name
|
Symbols
|
Context
|
Alternate Spellings
|
Prefixes
|
|
|
|
|
|
|
|
joule
|
J
|
SI *
|
joules
|
SI
|
|
electronvolt
|
eV
|
SI *
|
electronvolts
|
SI
|
|
hartree
|
E0
|
Atomic *
|
hartrees
|
SI
|
|
erg
|
|
standard *
|
ergs
|
SI
|
|
watt_hour
|
Wh
|
standard *
|
watt_hours
|
SI
|
|
ton
|
|
TNT
|
tons
|
SI
|
|
|
|
|
|
|
|
calorie
|
cal
|
thermochemical *
|
calory, calories
|
SI
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
`15degC`
|
|
|
|
|
|
`20degC`
|
|
|
|
|
|
|
|
|
|
Calorie
|
Cal
|
thermochemical *
|
Calories
|
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
`15degC`
|
|
|
|
|
|
`20degC`
|
|
|
|
|
|
|
|
|
|
British_thermal_unit
|
Btu
|
thermochemical *
|
British_thermal_units
|
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
`39degF`
|
|
|
|
|
|
`59degF`
|
|
|
|
|
|
`60degF`
|
|
|
|
|
|
|
|
|
|
therm
|
te
|
thermochemical *
|
therms
|
SI
|
|
|
|
IT
|
|
SI
|
|
|
|
mean
|
|
SI
|
|
|
|
EU
|
|
SI
|
|
|
|
US
|
|
SI
|
|
|
|
|
|
|
|
quad
|
|
thermochemical *
|
quads
|
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
|
|
|
|
Q_unit
|
|
thermochemical *
|
Q_units
|
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
|
|
|
|
Celsius_heat_unit
|
Chu
|
thermochemical *
|
Celsius_heat_units
|
|
|
|
|
IT
|
|
|
|
|
|
mean
|
|
|
|
|
|
`15degC`
|
|
|
|
|
|
`20degC`
|
|
|
|
|
|
|
|
|
|
planck_energy
|
|
planck *
|
planck_energies
|
|
|
|
|
|
An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively. Refer to a unit in the Units package by indexing the name or symbol with the context, for example, joule[SI] or Cal[thermodynamic]; or, if the context is indicated as the default, by using only the unit name or symbol, for example, joule or Cal.
|
|
|
The units of energy are defined as follows.
|
|
|
An electron volt is defined as joule, that is, the product of the charge of an electron in coulombs with a joule per coulomb.
|
|
|
An erg is defined as joule.
|
|
|
A watt hour is defined as joules.
|
|
|
A ton of nuclear equivalent TNT is equal to thermochemical calories.
|
|
|
An EU therm is defined as joules.
|
|
|
A US therm is defined as joules.
|
|
|
A planck energy is defined as a planck mass times planck length squared per planck time squared.
|
|
|
The Calorie
|
|
|
•
|
For each context of the calorie, there exists a unit, the Calorie, that is by definition times the value. Therefore, a Calorie is a kilocalorie.
|
|
|
A 15 degree Celsius or 20 degree Celsius calorie is approximately the amount of energy required to raise the temperature of gram of water by degree Celsius to 15.5 or 20.5 degrees Celsius, respectively.
|
|
|
A thermochemical calorie is defined as joules.
|
|
|
A International Table calorie is defined as joules.
|
|
|
A mean calorie is the energy required to raise the temperature of gram of water from degrees Celsius to degrees Celsius, and is approximately joules.
|
|
|
|
British Thermal Units
|
|
|
|
A 39 degree Fahrenheit, 59 degree Fahrenheit, or 60 degree Fahrenheit calorie is the approximate amount of energy required to raise the temperature of pound of water by degree Fahrenheit to 39.5, 59.5, or 60.5 degrees Fahrenheit, respectively.
|
|
|
A thermochemical British thermal unit is defined by the relationship: thermochemical British thermal unit per pound degree Fahrenheit equals thermochemical kilocalorie per kilogram kelvin.
|
|
|
A International Table British thermal unit is defined by the relationship: International Table British thermal unit per pound degree Fahrenheit equals International Table kilocalorie per kilogram kelvin.
|
|
|
A mean British thermal unit is the energy required to raise the temperature of pound of water from degrees Fahrenheit to degrees Fahrenheit.
|
|
•
|
For the thermochemical, International Table, and mean contexts, there are the following associated units.
|
|
|
A therm is defined as British thermal units.
|
|
|
A quad is defined as British thermal units.
|
|
|
A Q unit is defined as British thermal units.
|
|
|
|
Celsius Heat Units
|
|
|
|
A 15 degree Celsius or 20 degree Celsius heat unit is the approximate amount of energy required to raise the temperature of pound of water by degree Celsius to 15.5 or 20.5 degrees Celsius, respectively.
|
|
|
A International Table Celsius heat unit is defined by the relationship: International Table Celsius heat unit per pound equals International Table kilocalorie per kilogram.
|
|
|
A thermochemical Celsius heat unit is defined by the relationship: thermochemical Celsius heat unit per pound equals thermochemical kilocalorie per kilogram.
|
|
|
A mean Celsius heat unit is the energy required to raise the temperature of pound of water from degrees Celsius to degrees Celsius.
|
|
|
|
|
Examples
|
|
|
|
|
