I read this question on my Physics book and I'm still wondering whether my answer is right. My first thought is that the elevator is accelerating downwards. If it were accelerating upwards the briefcase would fall to the floor even quicker than if the elevator was not accelerating at all.
Then, the question is, how much is it accelerating? My answer is $a \ge g$. If the acceleration of the elevator is the same as that due to gravity, the elevator and the briefcase will experience the same acceleration, and the briefcase will never touch the floor. If, on the other hand, the acceleration of the elevator is greater than the acceleration of the suitcase, then the elevator is moving faster than the suitcase and the suitcase will eventually touch the elevator's roof.
Is my reasoning correct? I found a good explanation online, but they claim $a = g$ is the only right answer. Am I right to think that $a > g$ is plausible too?