   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.
1 12-15 total hrs day.  Yes...a 7 month old should be getting 2 naps during the day, usually from 10am-11:30ish and again around 1ish-3ish. And to bed no later than 8pm. They are usually up by 5:30am or 7am. HOWEVER....at 7 months baby start to transition from 2 naps a day down to 1 nap per day. www.sleeplady.com is an excellent resource to know how much sleep a baby-young child should get, why it is important....and most importantly the step by step guide of how to make it happen.