You know that a collision must be “elastic” if: (A) The colliding objects stick together. (B) The colliding objects are stretchy or squishy. (C) The sum of the final kinetic energies equals the sum of...

You know that a collision must be “elastic” if:

(A) The colliding objects stick together.

(B) The colliding objects are stretchy or squishy.

(C) The sum of the final kinetic energies equals the sum of the initial kinetic energies.

(D) There is no change in the internal energies of the objects (thermal energy, vibrational energy, etc.).

(E) The momentum of the two-object system doesn't change.