In other words forces acting on a body originate in other bodies that makeup its environ-ment.
Any single force is only one aspect of a mutual interaction between two bodies.
WORK Work is done when a force succeeds in over-coming a body s inertia and moving the body in the direction the force is applied. The formula is where W is work, F is force and d is the distance moved. The amount of work done is the product of the magnitude of the force and the distance moved. In the metric CGS system, force is measured in dynes, distance is measured in cen-timeters, and work is denoted in ergs. An erg is the work done by a force of one dyne exerted for a distance of one centimeter.