Inelastic collision

An inelastic collision, in contrast to an <a href="/facts/Elastic_collision/fu8AujA2">elastic collision</a>, is a <a href="/facts/Collision/0a3WSqod">collision</a> in which kinetic energy is not conserved due to the action of <a href="/facts/Friction/d0108Rpu">internal friction</a>.
In collisions of macroscopic bodies, some <a href="/facts/Kinetic_energy/aJRxUd4p">kinetic energy</a> is turned into vibrational energy of the <a href="/facts/Atom/FoQ4kGN5">atoms</a>, causing a <a href="/facts/Heat/FjDGssCs">heating</a> effect, and the bodies are deformed.
The <a href="/facts/Molecule/N9ljSfFq">molecules</a> of a <a href="/facts/Gas/hVVAoodV">gas</a> or <a href="/facts/Liquid/t9GkLWzt">liquid</a> rarely experience perfectly <a href="/facts/Elastic_collision/fu8AujA2">elastic collisions</a> because kinetic energy is exchanged between the molecules' translational motion and their internal <a href="/facts/Degrees_of_freedom_(physics_and_chemistry)/Rrjl0lnq">degrees of freedom</a> with each collision. At any one instant, half the collisions are – to a varying extent – inelastic (the pair possesses less kinetic energy after the collision than before), and half could be described as “super-elastic” (possessing more kinetic energy after the collision than before). Averaged across an entire sample, molecular collisions are elastic. 
Although inelastic collisions do not conserve kinetic energy, they do obey <a href="/facts/Conservation_of_momentum/TTkGv5eY">conservation of momentum</a>. Simple <a href="/facts/Ballistic_pendulum/7yQLVNQn">ballistic pendulum</a> problems obey the conservation of kinetic energy only when the block swings to its largest angle.
In <a href="/facts/Nuclear_physics/fzQbt1aF">nuclear physics</a>, an inelastic collision is one in which the incoming <a href="/facts/Subatomic_particle/tMEzcTWQ">particle</a> causes the <a href="/facts/Atomic_nucleus/orpIm5Xl">nucleus</a> it strikes to become <a href="/facts/Excited_state/czcLYNnr">excited</a> or to break up. <a href="/facts/Deep_inelastic_scattering/0kB9Leaf">Deep inelastic scattering</a> is a method of probing the structure of subatomic particles in much the same way as Rutherford probed the inside of the atom (see <a href="/facts/Rutherford_scattering/pDrXNfmK">Rutherford scattering</a>). Such experiments were performed on <a href="/facts/Proton/clCjepXP">protons</a> in the late 1960s using high-energy <a href="/facts/Electron/L0KBo5cW">electrons</a> at the <a href="/facts/Stanford_Linear_Accelerator/CzX2afas">Stanford Linear Accelerator</a> (SLAC). As in Rutherford scattering, deep inelastic scattering of electrons by proton targets revealed that most of the incident electrons interact very little and pass straight through, with only a small number bouncing back. This indicates that the charge in the proton is concentrated in small lumps, reminiscent of Rutherford's discovery that the <a href="/facts/Electric_charge/xxsBfmlB">positive charge</a> in an atom is concentrated at the nucleus. However, in the case of the proton, the evidence suggested three distinct concentrations of charge (<a href="/facts/Quark/hwuuVkV5">quarks</a>) and not one.

Inelastic collision open-in-new

Inelastic collision