   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.
We are in the mist of the 18 month sleep regression; week 2. It is not every night, but 2 to 3 nights a week of terrible sleep, so far anyway. He sleeps great at daycare for naps, not so great for naps on the weekends with us, and bedtime is hit or miss these days regardless of the same routine since 3 months old.n week two of the 18 month sleep regression. This one is every bit as brutal as the 4 month and way worse than the 9 or 13 month. Resorting to co-sleeping with a thrasher and nursing aaaaaaall night long. Ugh.