   A heavier plane has more momentum (when thrown at the same speed),  but it's also got more downward force acting on it. If it has the  same wing area, though, it has the same lift, so it drops more  quickly than a light plane (objects fall at the same speed only in  the absence of air resistance).
By 2 months, baby's bedtime should be between 6:00-8:00pm and should occur about 1 hour after the last nap ends. 3 months: babies this age should be on a solid 4 nap schedule with the last nap of the day ending by 5:00pm.
I think it's pretty normal how many hours my newborn sleeps though. My two week old only sleeps for about 1 1/2-2 1/2 hours at a time at night and when he gets up in between his sleep time he is extremely fussy. This is my first baby and it is extremely frustrating. He sleeps well and is never ever fussy during the day. He just likes to be a terror at night.