   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.
In fact, the average one to two-week-old baby will likely sleep for about 16 1/2 hours a day. Of course that won't all be at one time, but hopefully, you will get one stretch of four of five hours, and then shorter periods of two or three hours of sleep at a time.