It is used to model many situations in real life where a mass oscillates about an equilibrium. For an unstable equilibrium point, if the object is disturbed slightly, it does not return to the equilibrium point.Ĭonsider the marble in the bowl example. Simple harmonic motion (SHM) is a type of oscillating motion. The stable equilibrium point occurs because the force on either side is directed toward it. If an equilibrium point is stable, a slight disturbance of an object that is initially at the stable equilibrium point will cause the object to oscillate around that point. (See Potential Energy and Conservation of Energy.) Stability is an important concept. The points x = A and x = −A are called the turning points. Since the force on either side of the fixed point points back toward the equilibrium point, the equilibrium point is called a stable equilibrium point. In this case, the block oscillates in one dimension with the force of the spring acting parallel to the motion: This potential energy is the energy stored in the spring when the spring is extended or compressed. The force of the spring is a conservative force (which you studied in the chapter on potential energy and conservation of energy), and we can define a potential energy for it. If the only result is deformation, and no work goes into thermal, sound, or kinetic energy, then all the work is initially stored in the deformed object as some form of potential energy.Ĭonsider the example of a block attached to a spring on a frictionless table, oscillating in SHM. That is, whether you pluck a guitar string or compress a car’s shock absorber, a force must be exerted through a distance. To produce a deformation in an object, we must do work.