In a collision between an electron and a hydrogen atom, why is it useful to select both objects as the system? Pick all that apply: (A) The total momentum of the system does not change during the...

In a collision between an electron and a hydrogen atom, why is it useful to select both objects as the system? Pick all that

apply:

(A) The total momentum of the system does not change during the collision.

(B) The sum of the final kinetic energies must equal the sum of the initial kinetic energies for a two-object system.

(C) The kinetic energy of a two-object system is nearly zero.

(D) The forces the objects exert on each other are internal to the system and don't change the total momentum of the

system.

(E) During the time interval from just before to just after the collision, external forces are negligible.