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.
Balanced forces. When two forces acting on an object are equal in size but act in opposite directions, we say that they are balanced forces. If the forces on an object are balanced (or if there are no forces acting on it), this is what happens: a stationary object stays still a moving object continues to move at the same speed and in the same direction