The problem specified “freefall”, so thrusters are out. But I agree that it’s underspecified—there are way too many things which fit so we are reduced to guessing what Thomas had in mind.
The initial conditions did not forbid dropping object A into a downdraft and object B into an updraft :-)
But here is another attempt: objects A and B open parachutes 3 seconds after passing altitude X. Object B starts at altitude X, accelerates from zero for three seconds, and then radically slows down. Object A starts higher, so when it passes altitude X it is already going fast and so in three seconds is capable of passing B which is already braked by a parachute.
The problem specified “freefall”, so thrusters are out. But I agree that it’s underspecified—there are way too many things which fit so we are reduced to guessing what Thomas had in mind.
It is not what I have in mind. Anything goes, which does not break the initial conditions.
The initial conditions did not forbid dropping object A into a downdraft and object B into an updraft :-)
But here is another attempt: objects A and B open parachutes 3 seconds after passing altitude X. Object B starts at altitude X, accelerates from zero for three seconds, and then radically slows down. Object A starts higher, so when it passes altitude X it is already going fast and so in three seconds is capable of passing B which is already braked by a parachute.
Yes, well. There is some wit here again. The best solution I have in mind don’t require an atmosphere at all.
Well, maybe just for the sake of the liquid ocean water. Which is only for the sake of “a mountain and a valley soulution” prevention.