   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.
Baby Sleep Schedules. 1  12 1/2 hours by six months, including about nine hours at night; infants of this age should be able to sleep through the night and two or three naps during the day. 2  12 hours by nine months, including about nine hours at night and two naps during the day.