   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.
At 4 months, all naps should be ending by 5:00pm with bedtime happening about 2-2.25 hours after the last nap ends. So again, this means that bedtime should not be much later than 7:15pm. 5 months: Babies at this age should be solidly on a 3 nap schedule.