An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Elastic collisions occur only if there is no net conversion of kinetic energy into other forms.
During the collision of small objects, kinetic energy is first converted to potential energy associated with a repulsive force between the particles (when the particles move against this force, i.e. the angle between the force and the relative velocity is obtuse), then this potential energy is converted back to kinetic energy (when the particles move with this force, i.e. the angle between the force and the relative velocity is acute).
The collisions of atoms are elastic collisions (Rutherford backscattering is one example).
The molecules—as distinct from atoms—of a gas or liquid rarely experience perfectly elastic collisions because kinetic energy is exchanged between the molecules’ translational motion and their internal degrees of freedom with each collision. At any one instant, half the collisions are, to a varying extent, inelastic collisions (the pair possesses less kinetic energy in their translational motions after the collision than before), and half could be described as “super-elastic” (possessing more kinetic energy after the collision than before). Averaged across the entire sample, molecular collisions can be regarded as essentially elastic as long as black-body photons are not permitted to carry away energy from the system.
In the case of macroscopic bodies, perfectly elastic collisions are an ideal never fully realized, but approximated by the interactions of objects such as billiard balls.
When considering energies, possible rotational energy before and/or after a collision may also play a role.
Other articles related to "elastic, collision, elastic collision, collisions":
... We can describe Rutherford backscattering as an elastic (hard-sphere) collision between a high kinetic energy particle from the incident beam (the projectile ... Elastic in this context means that no energy is either lost or gained during the collision ... interactions, since in some circumstances a collision may result in a nuclear reaction, with the release of what can be very considerable quantities of energy ...
... colliding bodies at the point of contact, the other along the line of collision ... Since the collision only imparts force along the line of collision, the velocities that are tangent to the point of collision do not change ... The velocities along the line of collision can then be used in the same equations as a one-dimensional collision ...
... An elastic collision is one in which no kinetic energy is lost ... Perfectly elastic "collisions" can occur when the objects do not touch each other, as for example in atomic or nuclear scattering where electric ... a planet can also be viewed as a perfectly elastic collision from a distance ...
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