Public School, Deer Creek Minnesota, 1918 LakesnWoods.com Postcard and Postcard Image Collection - click image to enlarge Aerial view, Deer Creek Minnesota, 1972
Whenever work is done upon an object by an external force, there will be a change in the total mechanical energy of the object. If only internal forces are doing work (no work done by external forces), there is no change in total mechanical energy; the total mechanical energy is said to be conserved.
Increasing the distance from to reduces the force, but, since forces in Newton mechanics indicate how much potential energy is lost over space, , this separation requires of energy. Performing positive work equal to E units of energy, we can recede objects from r 0 to r 1 special units apart.