Additional images. 1  Dura mater (spinal section) 2  Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. 3  Diagrammatic transverse section of the medulla spinalis and its membranes. 4  Spinal cord. Spinal membranes and nerve roots.Deep dissection. 5  Spinal cord.
exists and is an alternate of . Amateur is a term that describes work done by nonprofessionals. <i>Amateur</i> is a term that describes work done by nonprofessionals.
When work is done by external forces (nonconservative forces), the total mechanical energy of the object is altered. The work that is done can be positive work or negative work depending on whether the force doing the work is directed opposite the object's motion or in the same direction as the object's motion.