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.
If the kinetic energy decreases, then the change in kinetic energy is negative. Since the work done equals the change in kinetic energy, the work done by this force must be negative. There are a couple of ways to handle this: 1  Remember that work = - force x distance in this case.his force will tend to increase the object's speed. If the object's speed increases, then its kinetic energy will increase. If the kinetic energy increases, the change in kinetic energy will be positive.