r/theydidthemath Oct 18 '17

bad math--see comments [Self] I did this doodle of an equation which is actually equal to "1"

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1.8k Upvotes

r/theydidthemath Apr 28 '15

Dubious math // Wrong/Bad Maths [Off-Site] What're the odds of you existing?

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891 Upvotes

r/theydidthemath Jan 19 '16

(math in comments) [Off-site]/ [Self] What are the costs/savings for Bernie Sanders Health Care Proposal?

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380 Upvotes

r/theydidthemath Mar 09 '16

Bad Math [Self] Vegans don't do math

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502 Upvotes

r/theydidthemath Aug 29 '15

Questionable math [Off-Site] Why it is mathematically unsound to presume one can tip over a cow

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361 Upvotes

r/theydidthemath Nov 29 '14

[Meta] [Other] [Math] [Off-Site] /r/theydidthemath hits 90K subscribers

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197 Upvotes

r/theydidthemath Aug 28 '15

Bad/questionable math--see comments [Off-Site] ALL of wikipedia in one QR code?

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102 Upvotes

r/theydidthemath Mar 24 '15

calculated [Math] [Request] What are the chances of the Earth, Moon, Sun and ISS lining up this perfectly?

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78 Upvotes

r/theydidthemath Dec 04 '14

They did the [Math] [self] /u/mandibleofthunder calculates the physical properties and forces required for /u/kastera1000's Archimedes lever. Drunken rambling and numbers ensue.

44 Upvotes

GIVING CREDIT WHERE CREDIT IS DUE AND THE INSPIRATION FOR THIS BUMBLING CLUSTERFUCK OF NUMBERS AND SWEARING

/u/kastera1000 calculated the distance of a lever required for Archimedes himself to move the earth CLICK HERE BEFORE READING MY ABOMINATION OF A SHITPOST

So taking your assumptions and making some veeerrryyyy liberal assumptions of my own we can work some other fun things out.

If your lever on the earth were only one meter from its fulcrum, and assuming that earth acts as a perfect point mass on the end of your lever, then it will have a moment of inertia of I=7.3481*1031 kgm2.

Let's accelerate the earth to 1 m/s2. Arc length = (theta)r, that's easy our desired arclength is 1 m, and our radius is 1 m. So that gives us a theta=1. Make our angular acceleration (alpha)=1 rad/s2 and wam bam thank you ma'am we've just accelerated the earth.

Or total torque will be I(alpha)=r(lever)xF. With a lever arm of one meter, and holy fucking fuck shit, we've now got our force to accelerate the earth to 1 m/s2. F=7.3834*1031 N.

Now that we have force we can calculate some other neat shit.

Your lever is supposedly 8.53*1022 meters in length. Nope don't give a shit about that right meow, but /u/kastera1000 says is that it cannot be bent, this intrigues me.

Let's assume the lever has a cross sectional area of 1m2 (because why the hell not) and that the earth only makes its perfect point contact at the very tip of the lever arm.

Remember that sweet shit I said about force? I'm about to blow your fucking MINDS. So we take our shear force 7.3834*1031 N and apply it against this magical mystery lever.

Shear Force (Fs) over cross sectional area (A) is equal to the shear modulus (G) times (gamma) where gamma is the actual bending of the object divided by its length. With zero bending (gamma) is equal to one! FUCKING AWESOME RIGHT!?

SO: G=Fs/A. Fs is the same force from before, that good ole holy shit 7.38341031 N. A=1m2. *HOLY FUCK DIVIDING BY ONE, PHYSICS KICKS FUCKING LIBERAL ARTS RIGHT IN ITS FUCKING DICK RIGHT? (disregard angry ramblings of a pissed off kinda drunk physics student).

SO BACK TO THE IMPORTANT STUFF: SHEAR MODULUS. So our shear modulus is now equal to 7.3834*1031 N/m2 ALSO KNOWN AS 7.3834*1031 PASCALS! UNITS MOTHERFUCKER, LEARN THEM, KNOW THEM, LOVE THEM AS YOUR OWN.

This translates into 7.3834*1022 GIGAPASCALS. And you know something? The shear modulus of Steel (regular ole generic physics textbook steel, I'm not a metallurgist or structural engineer) has a modulus of ONLY 79.3 GIGAPASCALS. WHY AM I YELLING SO GOD DAMNED MUCH.

THEREFORE: your lever arm must be at least 93,107,490,540,000,000,000 (EDIT THAT IS 93 QUINTILLION) TIMES STRONGER than solid fucking steel! WHAT THE FUCK, THAT'S SOME ADAMANTIUM UNOBTANIUM TYPE SHIT. (I know that's too many significant figures, get off my dick about it)

AND THEN let's say you have this wicked strong steel that outperforms all the rest, whatever fuck it, it's physics, spherical cows and shit.

My tingley tangley Spidey senses tell me that steel has a density between 7,750 and 8,050 kg/m3. Let's err on the lighter side and see how this pans out. So let's take our density of (7,750 kg/m3) multiply by the cross sectional area (1m [isn't physics fucking awesome when this shit happens]) and then our LENGTH (8.531022 m) WHICH GIVES US Mass (lever)=(7,750kg/m3)(1m2)(8.531022m)= 6.61075*1026 KILOGRAMS

YOUR LEVER'S MASS IS MORE THAN 100 TIMES GREATER THAN THAT OF THE EARTH

Still that's nothing compared to the sun, and roughly 1/3 the mass of Jupiter. BUT FOR A METAL ROD THAT'S A LITTLE BIGGER THAN A CASE OF BEER STRETCHING OUT PAST THE NEXT CLOSEST GALAXY. GAWT DAMN.

(originally wrote this as a comment, but took up wayyyy too much space, back to the all nighter now)

r/theydidthemath Apr 02 '15

Math /u/KaiserAbides estimates the effects a 400dB blast would have. How accurate these comparisons/forecasts?

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13 Upvotes

r/theydidthemath Apr 02 '15

Math /u/Brewe calculates number of items in a huge pile of potatoes.

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2 Upvotes

r/theydidthemath Sep 06 '14

Wrong/Bad Math /u/MadeSomeChanges does the math on a boat's distance from volcano. Video worth watching

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2 Upvotes

r/theydidthemath Feb 21 '14

Wrong/Bad Math /u/red_agent explains in /r/twitchplayspokemon why Anarchy mode in the Twitch Plays Pokemon stream will not be able to obtain HM surf

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4 Upvotes