tarâzmandi-ye pâydâr (#)
Fr.: équilibre stable
An equilibrium state of a system in which if a small perturbation away from equilibrium is applied, the system will return to its equilibrium state. An example is a pendulum hanging straight down. If it is pushed slightly, it will experience a force back toward the equilibrium position. It may oscillate around the equilibrium position for a while, but it will finally regain its equilibrium position. → unstable equilibrium.
Fr.: équilibre instable
An equilibrium state of a system in which if a small perturbation away from equilibrium is applied, the system will move farther away from equilibrium state. For example, mechanical equilibrium in which the potential energy is a maximum, as a sphere placed on top of a hill. Mathematically, if the second derivative of the energy with respect to the coordinate of interest is negative, the system is in an unstable equilibrium. → stable equilibrium.