I have read that the apparent weight of a person in a lift accelerating with acceleration 'a' downwards is given by: W = m(g-a) where 'm' is his mass so if a>g, then one feels negative apparent weight. But, it is also true that one becomes conscious of his weight only when he gets a reaction force from the surface. So, weight is actually the reaction force we receive. But, the minimum reaction force we can receive is 0, so we can't receive negative reaction force, so doesn't that mean that the minimum weight possible is zero. Then what about the equation when a>g?