Answer:
39.7 m
Explanation:
First, we conside only the last second of fall of the body. We can apply the following suvat equation:

where, taking downward as positive direction:
s = 23 m is the displacement of the body
t = 1 s is the time interval considered
is the acceleration
u is the velocity of the body at the beginning of that second
Solving for u, we find:

Now we can call this velocity that we found v,
v = 18 m/s
And we can now consider the first part of the fall, where we can apply the following suvat equation:

where
v = 18 m/s
u = 0 (the body falls from rest)
s' is the displacement of the body before the last second
Solving for s',

Therefore, the total heigth of the building is the sum of s and s':
h = s + s' = 23 m + 16.7 m = 39.7 m
I do not know what the school expects as an answer, but advantage of reflecting telescopes is that there is only one major reflecting surface, so it is quite easy to create a 6 or 8 inch telescope by an amateur, after adding on a prism and an eyepiece. (a microscope eyepiece could be used).
MY answer would be "easier to build". (it still takes tens of hours to grind and polish the single plane surface to a parabolic surface).
Electromagnetic waves all have the same velocity in the same medium. However, since frequencies vary widely, so do wavelengths.
Level 1: Plants and algae make their own food and are called producers. Level 2: Herbivores eat plants and are called primary consumers.
Yes, N2 is a triple bond.
Hope it helps!