The time from New Moon to Last Quarter is 22.15 days.
It would take 7 days
I would expect that period of time to comprise 3/4 of a full cycleof phases, or about 22.15 days.
The half life of Tritium is 12.32 years. it would therefore take 24.64 years for the amount to fall to a quarter of the original.
It should fall to a quarter.
It is important to know the days between spring frost and fall frost. Generally, there are about 180 days between these two times.
A quarter and and a pencils have little air friction and would not observed to fall at different velocity in normal classroom condition. It will be observed to fall to the ground at the same time.
Quarters and feathers would only fall at the same speed in a vacuum. In air, the quarter would fall faster, as it has less air resistance.
The year is 365 and a quarter days long so to compensate there is a leap year every 4 years. Otherwise after a while the calendar year would fall out of synch with the seasons. At some point, summer vacation would happen during the snowy part of the year.
91 days
Thursday
Spring and Fall Equinox
16 days till fall 2011