Question

What best describes the kinetic energy of two gas particles before and after a collision?

Answer 1

Kinetic energy is the energy possessed by the body when in motion. It is calculated by 1/2mv² where m is the mass of the body and v is the velocity.
Baring in mind that energy can not be created or destroyed but can only be transformed from one form to another (law of conservation of energy) then when two bodies collide the total kinetic energy of the two particles stays the same (kinetic energy is preserved). This is in the case of perfectly elastic collision, however, during inelastic collisions the kinetic energy is transformed to other forms of energy such as heat, sound and energy used in bond breakage.