It is important to notice that the Newton's cradle is commonly taken as the hallmark of perfectly elastic collisions, thus with elasticity near 1, used frequently in classrooms as a pedagogic demonstration of some physics principles (but see Gauld, 2006).
From an ecological point of view, an elasticity value within this range could be expected, since perfectly elastic collisions are seldom observed and near perfectly plastic collisions are much more frequent.
Descriptively, the device is the hallmark of the so called perfectly elastic collisions--given an encounter between two bodies, an elastic collision is said to take place when the ratio of relative speeds after and before the impact--coefficient of restitution -, equals 1.
In these equations, e refers to elasticity or coefficient of restitution--the ratio of relative speeds after and before a collision--varying between 1, a perfectly elastic collision, and 0, a perfectly plastic collision.
This is a general well-known result in the classical mechanics of elastic collisions valid even in relativistic mechanics) which we will make use of later.
This is the supertask, an illustration of how the total initial energy of the system of particles 1/2 [mv.sup.2] can disappear by means of an infinitely denumerable number of elastic collisions, in each one of which the energy is conserved.