It’s the Final Week!!
Chapter 20: 地球ドーナツ
Participants
Mark your participation status by voting in this poll
-
I’m reading along
-
I’m still reading but I haven’t reached this part yet
0 voters
2 Likes
Interesting last chapter with the usual amount of weirdness. It seems we won’t have any more 穴掘り部 after this, so I’m looking forward to what they’ll focus on next!
Can anyone read the kanji after 庭 in page 131? Is it 庭師?
2 Likes
Looks like it to me as well.
And wow, this was a wild ride. There was a lot of science talk towards the end, but I somehow got through it.
I’m super intrigued by the physics of this place, and what 白いおまわりさん’s role is.
3 Likes
Well now that all y’all have finished, I’ve finally managed to get my hands on a copy, so I guess I’ll start following along behind. 
11 Likes
It’s worth it! It’s been a wonderful manga. 
2 Likes
I went for 庭師 (gardener) too, presumably referring to 白いおまわりさん. As alluded to by Shimeji she appears prominently back in chapter 7, but reading again I don’t think that gave us any more insight into who she is.
The picture on page 128 reminded me of Malagueta beach in Malaga…
Chapter 25 appeared in Comic Cune this month so hopefully we will get a volume 3 towards the end of the year!
Summary
4 Likes
Ooh, nice! Something to look forward too! 
1 Like
Ooh that would be great, I’m really enjoying this series 
3 Likes
And finished!
So, uh… yeah. That was a thing. (One idly wonders whether the flounder/concrete engine provides a greater motive force than the cat/buttered-toast engine.)
The Truman Show reference in chapter 17 was a surprise. And it vaguely gets touched on in dialogue, but in chapter 18, all of those 陶ナツ are topologically identical. One wonders if Sensei is digging to Brazil in order to turn the Earth itself into such a figure…
Chapter 20, the book discusses the equations necessary to solve for the depth of the hole, but (perhaps not entirely surprisingly) doesn’t actually work through the problem. The solution is as follows:
(in David Tennant voice) Physics, physics, physics
The three equations are:
(1) h = 1/2 g t1²
(2) h = t2 V
(3) T = t1 + t2
T is the variable that we’re measuring, and h is what we want to find, so we need to eliminate t1 and t2. We do this by rearranging equations (1) and (2) to make t the subject, and substitute into (3).
So (1) becomes: t1 = √(2h/g)
And (2) becomes t2 = h/V
So (3) becomes T = √(2h/g) + h/V
With a great deal of rearranging and quadratic equations and substituting in known values for g and V, we eventually get
h = (-75.5424 + 169.492√(0.2039+0.118 T))²
With various assumptions like there’s no air resistance on the rock, gravity is constant, the speed of sound doesn’t change as the hole gets deeper, and so forth. All of them fairly poor assumptions when you’re talking about drilling a hole clean through the planet.
Fun fact for page 118: if the Earth weren’t six thousand degrees at the core, and if the characters weren’t slowed by air resistance, and if the Brazil end of the hole isn’t on top of a mountain or something, then they would arrive at Brazil pretty much exactly as depicted in Majime’s imagination - moving slow enough to simply hop out of the hole.
7 Likes
isn’t that basically the hyperloop concept 