ABSTRACT
Stability is not a clearly defined concept for all disciplines, but some simple analogies can be used to illustrate an intuitive notion of stability. Often we think in terms of the dynamics of a rigid body as shown in Fig. 11.1. There, slight disturbances to the equilibrium positions can be demonstrated in terms of stability. If the ball tends to return to the bottom of the trough, as the result of a slight disturbance, the equilibrium position is said to be stable. However, as in the case of Fig. 11.1b, if a small disturbance leads to a finite motion of the ball, the critical condition is called unstable. If the ball remains at the same vertical level, the equilibrium configuration is referred to as being neutral.
