I recommend that you create a formula/summary sheet as you read through the notes. That
sheet should be sufficient as a reference to answer the questions of the quiz. If not, consider updating your
sheet!
After this course is finished, your sheets — representing your own “personalized” version of the material — will
hopefully be useful to you.
The questions are ordered according to my subjective assessment of their difficulty: “easy” to ”difficult”. In principle,
I’m trying to cover the range from relatively straightforward to challenging, without so many questions that you get
bored.
Good luck! The questions may be accessed on the LHS of this screen.
On a
web-page describing the proposed Thirty Meter Telescope (TMT), a potential site is described as
being:
“Located above approximately 40 percent of Earth’s atmosphere.”
Recall that the “scale height” of the earth’s atmosphere is
≈8.5km.
The TMT site has an elevation above sea-level of approximately:
Choice (d) is Correct!
By
considering the density dependence of the earth’s atmosphere to be
ρ=ρ0e−z∕H,
where
ρ0 is the density
at sea-level and
H
the scale-height, we can compute the fraction of the total mass of the atmosphere beneath a certain height
z
as:
f=1−e−z∕H.
Setting
f=0.4 and rearranging
gives
z≈4300m, which is close
to the value of
z≈4050m
given for Maunakea on the TMT web-site.