# unstable equilibrium

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Related to unstable equilibrium: neutral equilibrium

## unstable equilibrium

[¦ən′stā·bəl ē·kwə′lib·rē·əm]
(physics)
An equilibrium state of a system in which any departure of the system from equilibrium gives rise to forces or tendencies moving the system further away from equilibrium; for example, mechanical equilibrium in which the potential energy is a maximum, as a sphere sitting on top of a hill.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## unstable equilibrium

The condition of a structure in a state of equilibrium; when a slight disturbance is applied to the structure and then removed, the structure does not return to its original equilibrium position. Compare with stable equilibrium.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
P1, P2, and P3 are general unstable equilibrium points.
The solid curve stands for the stable equilibrium and the dashed curve stands for the unstable equilibrium. Note that, for [[beta].sub.1] = 30 and [R.sup.*.sub.1] > 1, [[beta].sub.2] = 0 such that system (1) has a unique positive high-criminality equilibrium (see case (i) of Theorem 1 and (12)).
Near the unstable equilibrium point [E.sub.0], we can find a stable periodic solution for b < [b.sub.0].
Now, setting the parameter a = 2.5, the five unstable equilibrium points in system (2) are [s.sub.0] = (0, 0,0), [p.sup.+] = (3.5355,1.7202,1.0136), [p.sup.-] = (-3.5355,-1.7202,1.0136), [q.sup.+] = (3.5355, -3.4880, -2.0553), and [q.sup.-] = (-3.5355,3.4880, -2.0553), respectively.
A chaotic attractor appears, which corresponds to a unstable equilibrium point, indicating the chaotic attractor is a self-excited attractor.
When [phi] < 0 with [absolute value of ([phi])] [much less than] 1, 0 is unstable; when 0 < [phi] [much less than] 1, 0 is locally asymptotically stable, and there exists a positive unstable equilibrium.
The EU is in an unstable equilibrium: Small disturbances can produce large changes.
A classical system may be in stable, neutral, or unstable equilibrium. A neutrosophic system may be in quasi-stable, quasi-neutral or quasi-unstable equilibrium, and its potential energy respectively quasi-minimum, quasi-null (i.e.
If there was any doubt before the latest wave of violence, one thing is now clearthe conflict cannot be "managed." It is impossible to calibrate an inherently unstable equilibrium, and it is cynical that both sides in this conflict have attempted to do this for such a long period of time.
In ecology, the existence of travelling wave solutions connecting two equilibria means that the unstable equilibrium is taken over by the stable one in space as time increases.

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