# meter—kilogram-force—second systems of units

A metric system used by engineers, who are much more concerned with force than with mass as such, and so prefer to work in a system with base units of length, force and time instead of length, mass and time. Abbreviation, m-kgf-s. It has the same relation to the meter-kilogram-second system as the British Engineering system of units has to the foot-pound-second system. Such systems are often called technical or gravitational systems, and this system is often called the metric technical system.

The unit of force is the kilogram-force. In Germany and Eastern Europe it is sometimes called the kilopond.

The unit of mass in the m-kgf-s system is somewhat confused. It was once called the hyl, but unfortunately that term has been used in two senses:

1) a mass such that a gram-force acting on it will accelerate it 1 meter per second per second, about 9.806 65 × 10−3 kilograms; or

2) a mass such that a kilogram-force acting on it will accelerate it 1 meter per second per second, about 9.806 65 kilograms (the term kilohyle always applies to this second sense).

To avoid confusion it is best to use the term metric-technical unit of mass (symbol, TME), which always has the second meaning. It has also been called the metric slug, alluding to the unit of mass in the British gravitational system.

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