Shiva is the property of Energy. Uma is quiet, potential energy. durgA is impassable the kinetic energy which cannot be made zero (absolute zero impossible).
Universe matter forms evolve on the matted hair of Shiva. Refer Shiva thandava stotram here.
This evolution is driven by durgA, the kinetic energy, who makes the matted hair of Shiva beautiful by enabling evolution of newer and newer matter forms. durgA does this by winning over powerful (mahiSa) non-evolving (asura) matter forms. This is the crux of mahisasura mardhini stotram.
Uma is the potential in us. We invoke this durgA, the kinetic energy, by utilizing our potential, and win over powerful (mahiSa) non-evolving (asura) characteristics in us.