The unit of work depends on the type of work to be performed. The most common international systems of units (SI) recognize the work unit as joule, denoted by “J”. Additionally, there are many other types of units used to measure work.
The most common units for measuring work are as follows.
Joules (J):
The joule is the standard unit of work and energy in the International System of Units (SI). One joule is equal to the work done when a force of one newton moves an object one meter against the force.
Calories (cal):
A calorie is a unit of energy and work that is mainly related to nutrition. It is defined as the amount of heat required to increase the temperature of one gram of water by one degree Celsius.
Kilocalorie (kcal):
The kilocalorie (or calorie with a capital “K”) commonly used in the context of food energy is equal to 1,000 calories.
Erg (erg):
The erg is a unit of work or energy in the centimeter-gram-second (CGS) system. One erg is the work done by a force of one dyna acting over a distance of one centimeter.
Foot-pounds (ft-lb):
The foot-pound is a working unit in British and American measurement systems. It represents the work done when a force of one pound moves an object one foot against the force.
Newton meter (N·m):
The newton meter is equivalent to a joule and is often used interchangeably in the context of work and energy, particularly in physics and engineering.
Kilowatt-hour (kWh):
Although the kilowatt-hour is primarily a unit of energy, it is often used in discussions about work, especially in the context of electricity consumption. A kilowatt-hour corresponds to the work that a kilowatt of energy does in one hour.
British Thermal Unit (BTU):
The British Thermal Unit is a unit of work or energy commonly used in the United States, primarily in connection with heating and cooling systems. One BTU is the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit.
Foot pound (pdl·ft):
The foot pound is a unit of work in the foot-pound-second (FPS) system. It represents the work done when a force of one pound moves an object one foot against the force.
Calories (International Table) (cal): This calorie is based on the international table of specific heat capacity and is defined as 1/4,184 joules.
In addition to the units mentioned above, we use other work units to measure work smaller than joules.
They are as follows.
Erg (erg):
As already mentioned, the erg is a work unit of the CGS system and corresponds to a dina applied at a distance of one centimeter. It is a smaller unit and one joule is equivalent to 10 million ergs.
Electron volts (eV):
The electron volt is a unit of energy commonly used in particle physics and atomic-level calculations. One electron volt is equivalent to approximately 1.602 × 10−19 Joules.
Poundal foot (ft pdl):
The foot pound is a working unit of the FPS system, where one foot pound corresponds to one pound exercised at a distance of one foot.
Calories (International Table) (cal):
Although the calorie is primarily a unit of energy, it is also used in discussions about work. One calorie (International Table) is approximately equal to 4,184 joules.
Thermal (thm):
Therm is an energy unit in the area of heating, ventilation and air conditioning (HVAC). One therm is equal to 100,000 British Thermal Units (BTU) or about 105.5 megajoules.
These smaller units are often used in specific scientific or engineering contexts where the workload is relatively small.
