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/sci/ - Science & Math

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4616885 No.4616885[DELETED]  [Reply] [Original]

hey guys, /tg/ nerd here.

I have a math problem that's vexing the piss out of me, so I decided to ask those in the know with this kind of stuff...

so, ultimately, I'm trying to find the diameter of a giant iron sphere, if the sphere weighed 120 lbs... I was able to determine its volume, 6912.76154 cm^3, but after attempting the formula for diameter given volume, I got something like 36 feet, and I know a 36 foot wide sphere of solid iron weighs a fuck-load more than 120 lbs, so...

can you guys help me out?

pic related, the sphere will be a gargantuan giant's shot put. the putter in the pic is me.

>> No.4616899

>>4616885
The radius is .3877 feet so the diameter is .7754 feet (assuming your volume was correct)

>> No.4616901

I'll delete this thread when I get my answer, since I don't wanna shit up your board more than I must. if any kind anon would like to explain that function to me so don't fail so hard next time, that'd be awesome... but a simple answer would be sufficient, as long as you can show me how you got it.

>> No.4616905

7/10 , nearly had me there

>> No.4616911

>>4616899
huh... that doesn't seem right, either...

OK, so I must have failed harder than I thought. Iron's weight is 7.874 g/cm^3. if there's 453.59237 grams in a pound, then there's 57.6063462 cubic cm / lb of iron, so that x120 is
6912.76154... did I mess that up too?

>> No.4616912

4/3 pi * r^3 = volume

so r^3 = volume *3/(4pi)

r = cuberoot(volume *3/(4pi))

this is your answer in centimeters. now multiply by 2.54 to get the answer in inches.

looks like the radius is about about 2.5 feet. so you're looking at 5 feet

>> No.4616918

>>4616905
totally not trolling, just bad at math, man. this is seriously the first time I've ever posted in /sci/.

>> No.4616920

density of iron = 7.874 g/cm^3
1 pound = 453.59237 grams
120 pounds - 54,431.0844 grams
(54,431.0844 g)/(7.874 g/cm^3) = 6 912.76154 cm^3
so you are right on this

d = 2*cbrt(6912.76154*3/(4pi))
d = 23.6347485 ----->cm<------
23.6347485cm = 0.775418258 feet

fuck you 'murica

>> No.4616924

>>4616912
wow, well, thats a little disappointing, but I guess it makes the most sense...

now I kinda feel like I wanna make the shot even bigger... but if you guys don't feel like answering anymore of my questions, I'll understand and just delete the thread.

>> No.4616926

>>4616924
No don't listen to him, he is retarded

>>4616920
>>4616899
have it right

>> No.4616935

seriously? a 120 pound sphere of iron is only about nine and a half inches wide? fuck... thats way too small!

>> No.4616936

Mass of Cast Iron ball
(lb) Diameter
(in)
4 3.05
6 3.49
9 4.00
12 4.40
18 5.04
24 5.55
32 6.10
42 6.68

>> No.4616941

>>4616924
(2*cbrt(pounds*453.6*3/(4*pi*7.874)))*.0328

here plug this into wolfram for your answer with any pounds, this will find the diameter.

im too lazy to simplify the constants so just copypaste it.

>> No.4616948

>>4616936
ffffffffuuuuuuuck...

well, suppose I wanted a sphere that weighs a ton? 2000 lbs. how big is that?

>> No.4616953

>>4616948
(2*cbrt(pounds*453.6*3/(4*pi*7.874)))*.0328
(2*cbrt(2000*453.6*3/(4*pi*7.874)))*.0328
1.98 feet

>> No.4616968

there IS a method to my madness, but I assumed it was inconsequential to you folks. I'm building a Half-Ogre war-hulk/hulking hurler, D&D 3.5. wanna see exactly how big the crap he throws at people could be, with "shot putting" and "bowling" being his favored methods of attack... I dunno if that means anything to you though.

>> No.4616984

>>4616953
is that radius or diameter? not even 2 feet wide? damn.

well, you've all been helpful. thanks a lot. I think I got everything I needed. if I have more questions later, I might come back.

thanks, /sci/.

>> No.4617002

>>4616968
assuming orges have 3 times the strength of a human. and that the rate is direct with how much orge your are, a half orge would be able to lift 1.5 that of a strong human being.

normal strong humans can throw a shot put of around 10 pounds, around 6 pounds effectively to harm someone. 1.5*6 = 9.

so 9 pounds
(2*cbrt(9*453.6*3/(4*pi*7.874)))*.0328 = .32 feet

a normal human can bowl a 12 pound ball, around 8 to effectivly harm someone.

8*1.5=12

(2*cbrt(12*453.6*3/(4*pi*7.874)))*.0328 = .35 feet

I don't really understand why the diameter matters at all.
I also don't understand who would mate with an orge, that is not already an orge?