Stability implies an equilibrium that we can both observe and measure. Static stability suggests that there is no observable movement associated with the experimental system. Therefore the difference between static stability and dynamic stability centers around the difference between no movement versus movement. The term dynamic implies movement, while static suggests no movement within the time frames for our observations of any physical system.

One example of a static equilibrium is the addition of unequal weights slowly added to a two pan balance. The tilt of the balance from the horizontal position would be the new "static" equilibrium state (If you doubt that a balance will tilt, you should procure an old fashioned two pan balance and try it for yourself). Another example would be if you place something on a table top. The object placed on the table is statically stable. The object is statically stable, but may have significant potential energy that would be observed as kinetic energy if it fell off of the table.

Dynamic stability suggests repetitive movements that appear unchanged over the observed interval of observation. An example of this might be the chemical equilibrium of two chemicals, A and B, in equilibrium where A is converting to B and B is also converting back to A. The relative rates of the conversion of A to B and B to A establishes an observable overall equilibrium constant for these two chemical species under the specified experimental conditions such as temperature, pressure, etc. Another example would be the revolution of the earth and planets around the sun.

These are the essential differences in the definitions between static stability and dynamic stability. However, there are interesting variations that involve such dynamic systems as those termed "strange attractors" in chaos theory. The energy in these system may appear to be noisy, but the overall patterns appear stable. These dynamically stable systems may be important in explaining such disparate phenomena as heart arrhythmias and stable weather patterns. Although the basic differences between static and dynamic stability remain, the way that physical systems proportion the kinetic and potential energies remains an intriguing area for further scientifc research.

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