The term METRIC ENERGY UNIT is composed of three parts: ERG, which is a three-letter acronym for a metric energy unit. An ERG is a unit of energy or work equal to the amount of work done by a force of one dyne acting over a distance of one centimeter. It is also equal to 10−7 joules. The ERG is not an SI unit, but it is accepted for use with the SI. It is most commonly used in the measurement of mechanical work and energy, such as in the study of biomechanics.