   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.
You can start to plan regular naps and begin to establish bedtime routines when baby reaches about 6 months. Baby will now be sleeping about 15 hours a day, including naps. By 9 months babies begin to consolidate their naps down to 2, taking one in the morning and one in the afternoon.