An erg is a unit of energy in the CGS (Centimeter-Gram-Second) system. It is equal to the work done when a force of one dyne displaces its point of application by one centimeter.
Work Formula in CGS:
Work (erg) = Force (dyne)×Distance (cm)
In terms of CGS base units, 1 erg is expressed as:
1 erg = 1 gram cm2/s2
The word erg comes from the Greek verb ἔργov (ergon), which means work or task. The term ergon was used by Greek philosophers, notably Aristotle, to define an object’s function or task, such as the purpose of a tool or the activity of a living being.
The erg was the official CGS unit of energy, but the joule became the preferred measure of energy after the International System of Units (SI) was adopted in 1971. Despite this, the erg is still utilized in many fields where CGS units make computations easier, especially in surface chemistry, astronomy, and microscopy.