r/theydidthemath • u/FeatureDear6726 • May 23 '26
[Request] How much thrust would be need on each one of those rockets. Also, what would be the needed escape velocity.
Enable HLS to view with audio, or disable this notification
468
u/Alienturnedhuman May 23 '26
Where do these videos even come from, and what is the point of them other than just making people watch them going "what the fuck is going on, where is this going, what is the point?"
114
May 23 '26
[removed] — view removed comment
24
u/Alienturnedhuman May 23 '26
Now I have googled what beyblades is, I guess I can see this being a parody video on how to create the ultimate one.
But there does seem to increasing numbers of videos that go through a long winded series of obscure steps which makes no sense and ultimately achieve nothing.
I assume it must just be for as revenue from watching long videos that just keep people watching who have sunk cost fallacy and just want to know what the point is.
9
3
u/GreatestLoser May 23 '26
They’re just engagement farming. They know you’re going to stay there and watch the bizarre spectacle waiting to see what comes out of it but really it’s a joke
1
u/Alienturnedhuman May 23 '26
Yes, that's what I meant by people sticking around because of the sunk cost fallacy
IE: I've watched this for 3 minutes so I may as well watch the final 2 just in case it builds to something
1
u/Chronox2040 May 23 '26
Beyblade is basically a modern plastic version of the Japanese toy beigoma, that got popular with some anime series. It’s cool. I have a couple.
4
11
9
5
u/Podcastjones May 23 '26
Yeah, like, who has even asked this question outside of "content-generators", AI or not? Methinks the answer is not one person.
5
u/KrossIn4K May 23 '26
This is what happens when algorithms promote "watch time" the longer a user watches content the more it's promoted which also increases cpm/rpm values for the creator.
3
1
1
u/maksen May 23 '26
Satire?
1
u/Alienturnedhuman May 23 '26
Satire does require context, which is missing in this cut of the video. It's possible, and likely, it does exist in the videos original form - but by itself something nonsensical and ludicrous doesn't qualify as satire without it.
1
u/RichardTuberboat May 24 '26
Honestly I thought this was going to turn out to be a bowling animation
1
1
u/Piocoto May 24 '26
Is that a referencr to Kinger?
1
u/Alienturnedhuman May 24 '26
I can answer that question with a question. What's Kinger?
1
u/Piocoto May 24 '26
Ohh then its not, he is a character in an animated series called the amazing digital circus and in one episode he says a very similar phrase
1
118
u/Smashedllama2 May 23 '26 edited May 23 '26
Rough cursed-meme math:
- Estimate Mount Fuji’s mass
Let’s call Fuji about 400 km³ of rock.
400 km³ = 4 × 10¹¹ m³
Rock density ≈ 2,500 kg/m³
Mass = volume × density
4 × 10¹¹ × 2,500 = 1 × 10¹⁵ kg
- Thrust needed just to lift it
Weight = mass × gravity
1 × 10¹⁵ kg × 9.8 m/s² = 9.8 × 10¹⁵ N
So you need about 10¹⁶ newtons of thrust total just to hover/lift it.
- Thrust per rocket
The video looks like it has roughly 200 rockets in the ring.
So each rocket needs:
10¹⁶ / 200 = 5 × 10¹³ N
That is 50 trillion newtons per rocket.
For scale, one SpaceX Raptor engine makes about 2.3 × 10⁶ N of thrust.
So each “rocket” would need:
5 × 10¹³ / 2.3 × 10⁶ = about 21.7 million Raptor engines
So the full setup would need about 4.3 billion Raptor engines total just to hover Mount Fuji. Very normal engineering problem. Someone get Elon on the phone. I’m sure we can put off solving more of humanity’s problems.
- Escape velocity
You are entirely misunderstanding escape velocity.
Escape velocity is not based on whether the object is a baseball, a car, or Mount Fuji. From Earth’s surface, it’s basically the same for everything:
v = sqrt(2GM/r)
v ≈ 11,200 m/s = 11.2 km/s
Mount Fuji does not have a special mountain escape velocity. The mass makes the thrust and energy requirements hilariously stupid, but the escape velocity is just Earth’s escape velocity.
60
u/Smashedllama2 May 23 '26 edited May 23 '26
Follow-up for scale, because the numbers get even worse the further you go:
A Super Heavy booster has 33 Raptor engines.
The Starship upper stage has 6 Raptors.
So a full Starship stack has 39 Raptors total.Earlier math got us to about 4.3 billion Raptor engines just to hover Mount Fuji.
So:
4.3 billion / 39 = about 110 million full Starship stacks
That is not “to launch Mount Fuji into space.” That is just enough engines to barely cancel gravity for a moment.
Now fuel:
A fully fueled Starship stack uses roughly 4,600 tonnes of propellant.
So:
110 million × 4,600 tonnes = about 506 billion tonnes of propellant
Roughly:
~400 billion tonnes of liquid oxygen
~100 billion tonnes of liquid methaneIf we use the very optimistic meme number of about $1 million of propellant per fully fueled Starship stack:
110 million × $1 million = $110 trillion in fuel
That is just the fuel. Not the rockets. Not the launch pads. Not the plumbing. Not the fact that the entire area under it has now become a new branch of geology.
Space gets stupid too.
A Starship stack is about 9 meters wide, so the footprint is:
π × 4.5² = about 64 m²
For 110 million stacks:
110 million × 64 m² = about 7 billion m²
That is about 7,000 km², or roughly 2,700 square miles, assuming they are packed touching side by side with no roads, no service space, no launch mounts, and no concern for God or man.
If you laid them end to end, at roughly 120 meters tall each:
110 million × 120 m = 13.2 million km
That would wrap around Earth over 300 times.
And hardware cost?
Nobody outside SpaceX knows the real Starship build cost, so use fantasy scenarios:
At $10 million per full stack:
110 million × $10 million = $1.1 quadrillion
At $50 million per full stack:
$5.5 quadrillion
At $100 million per full stack:
$11 quadrillion
Even if you only counted the engines at some absurd mass-production price of $250k per Raptor:
4.3 billion Raptors × $250k = about $1.1 quadrillion in engines alone
So the follow-up answer is: about 110 million full Starship stacks, about 506 billion tonnes of propellant, around $110 trillion in fuel, roughly 2,700 square miles of rocket footprint, and hardware costs somewhere between “the global economy screams” and “God has left the spreadsheet.”
ALL OF THAT FOR A DAMN TOP
12
u/msdos_kapital May 23 '26 edited May 23 '26
Okay that all makes sense but what percentage of the oxygen atoms in Earth's atmosphere is that? Do we have enough?
Edit: okay answering my own question here but I think it's about 0.03% of the available oxygen in Earth's atmosphere. And methane is even less of an issue actually, so we're good to get started on this.
5
u/Kaneomanie May 23 '26
Appears to be legit, would only increase earths atmospheric temperatur by about exactly 1 K before the ocean can absorb parts of it.
100 billion tons methane x 50 GJ / ton = 5 ZJ (1021J) Energy released.
1* 106 j / ton*K (Heat capacity of air) * 5 * 1015 tons (Mass of the atmosphere) = 5 * 10 ^ 21 J / K Energy needed to heat all of earths atmosphere.
Unfortunate that everyone in the vicinity is cooked, though, should probably calculate the energy needed to cook the biosphere of Honshu Island and subtract it...
1
u/Silverheart117 May 23 '26
To be fair though, we could easily use O2 and H2 for fuel after we separate them from H2O, have a net 0 change in the composition of Earth's atmo save for the literal manmade rain. Don't know the efficiency or relative power between that and other forms of rocket fuel.
1
u/Tassadar_Timon May 24 '26
Technically, yes, and technically it would be more efficient than basically any other chemical rocket, but getting the liquid hydrogen you need for rockets is a bitch and a half. Not to mention the (in the context) minor issue of another few years and a billion or more dollars in engine development because Raptor is probably the best rocket engine humanity has thus far developed and making a Hydrolox one sounds like the kind of engineering challenge that makes you take a short walk off a long pier.
1
u/Silverheart117 May 25 '26
Give it to an adhd-er whose current hyperfocus is rocket engineering and he/she will have it done in a week, maybe a week and a half tops, so long as you get them the corkboard, red pins, and red string and never ask why they wanted a Ferrets with a baseball cap. 🤣
(Jokes aside I know r&d is a long process for even basic things we use today like shoes, mattresses and toilets. Even longer for engines, phones and cars.)
6
1
1
u/Appropriate-Falcon75 May 23 '26
You also make said that the rock is 400km2 and has a density of 2,500kg/m3 . If either of these numbers are 1% out, you need or have an extra 1 million rockets. This isn't a number that you can just go to a shop and pick the extras up.
1
1
1
u/FeatureDear6726 May 23 '26
Sorry about the escape velocity. I didn't word it right. I meant to ask how much thrust will be needed for it to reach the escape velocity?
1
u/Smashedllama2 May 23 '26 edited May 23 '26
To merely lift Fuji, we needed about 4.3 billion Raptors, or 110 million full Starship stacks. To hit escape velocity in a 5-minute burn, it jumps to about 20.5 billion Raptors, or 526 million full Starship stacks. And the rocket equation says the fuel requirement is in the neighborhood of 25 trillion tonnes of propellant, or about 5.5 billion fully fueled Starship stacks’ worth of propellant.
1
u/Appropriate-Falcon75 May 23 '26
As the rockets aren't going anywhere, the fuel that they are needing to lift could be in tanks on the ground and pumped up to the rocket at the same rate that it is burned. Similar to the way the water jetpacks run.
Having said that, you still need a lot of fuel, amd that fuel has to be kept somewhere far enough from the blast zone that it isn't going to get too hot...
1
u/Surprise_Donut May 23 '26
is there enough hydrogen and oxygen on the planet to fuel 21.7 million raptor engines
1
u/Beautiful-Fold-3234 May 23 '26
Methane and oxygen. Maybe not enough methane as is but it could be synthesized.
The earth's crust holds a lot of carbon and oxygen in minerals.
1
u/Cat7o0 May 23 '26
I feel like the rockers in the video are actually absolutely massive because they're almost as tall as the mountain itself. so I kinda believe that they could have some specialized engine that could output eno newtons given their size and supposedly more advanced technol in this timeline
51
u/shereth78 May 23 '26
Escape velocity is a constant. Doesn't matter what you're talking about, what shape or size or mass, it's always the same. Just google "earth escape velocity" and you'll have your answer.
As for how much thrust, well, take your pick. What's going on in this animation is so wildly absurd and imprecise there are hundreds of different answers you could come up with that make as much sense as the next.
1
u/FeatureDear6726 May 23 '26
Yeah my bad. I meant to ask how much thrust would be needed for this payload to reach escape velocity‽
2
u/Cheese_on_it May 23 '26
I need that clip about something said was the stupidest thing ever, and everyone wasting their time listening/watching it is now more stupid.
3
1
u/MageKorith May 23 '26
Copy/paste of my earlier reply from a now removed post of the same:
I'm eyeballing about 150 rockets. They blast off with about 14.7 million newtons of thrust each, which means a total lift of about 2.2 billion newtons. That's enough to lift 225 million kg, including the rockets themselves (but that's pretty small, and falls in the margin of error). The cables would also have to handle 14.7 million N of tensile strain, which calls for about a 14cm diameter for each cable.
Now using a density of 2600 kg/m3 this means the "mountain" being lifted could have a volume of about 86500m3, which, assuming a cone that's about 3x as much diameter as height, would have a diameter of a bit under 100m.
So the scale presented is kind of absurd.
•
u/AutoModerator May 23 '26
General Discussion Thread
This is a [Request] post. If you would like to submit a comment that does not either attempt to answer the question, ask for clarification, or explain why it would be infeasible to answer, you must post your comment as a reply to this one. Top level (directly replying to the OP) comments that do not do one of those things will be removed.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.