|
|
|
|
|
|
The zeptojoule (zJ) is equal to one sextillionth (10−21) of one joule. 160 zeptojoules is about one electronvolt.
The British thermal unit (Btu or BTU) is a traditional unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is part of the United States customary units.