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either my math is off or their math is off


Alpo

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I am attempting to find the volume of a bowl. Logically you should be able to consider the bowl as a sphere, and when you have the volume of the sphere cut it in half.

 

The bowl in question is 12 cm in diameter and 6 cm high. That sort of makes it look like it's exactly half of a sphere.

 

41Y-fKQjVVL._AC_UF894,1000_QL80_FMwebp_.

 

https://www.wikihow.com/Calculate-the-Volume-of-a-Sphere

 

Using the formula on that site

 

V=4/3π (R³)

4/3 pi is a constant. 4.188790...

The only thing I need to find is the cube of the radius.


D-12cm, H-6cm   these are the dimensions given for the bowl

 

R=6

R³ = 216
4/3π=4.19
V=904.8cc
1/2V = 452.5 cc

 

Did I skip a step somewhere? Because the site that is selling the bowl says the capacity of the bowl is 200 mL. While I dislike, intensely, the metric system, I do remember that a milliliter and a cubic centimeter are the same damn thing. So if I come up with 452 CCs and they come up with 200 mL, something's wrong somewhere.

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8 minutes ago, Texas Joker said:

How thick is the base? 

It does not say how thick the base is, but it would have to be awful damn thick to cut 450 down to 200.

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They don’t consider capacity to mean filled to the brim and they won’t give you a number with more than two significant digits, in this case they only gave you one.

 

now I suggest that you put 200 ml of water in it and then add 100 ml and consider which you would like to be a bowlful, 200 or 300. If you want to live dangerously add another 100.  In any case, 452 or not, nobody would advise you that 452 was the capacity of that bowl.

 

did you measure inside or outside?  It looks like outside which would be significantly off anyway.

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It's not really a sphere! More half of an oval shape as there's more curve as you get to the bottom.;)

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Your math is right except for some significant figures considerations (the presented measurements on the graphic already violate the rules).

 

If I assume a spherical bowl (well, semi-spherical),  and use 5 cm instead of 6 (for inner volume), I get 262 cubic cm. And I would not fill it full before trying to take my bowl to the table. The shape is more ovoid, the base is taller than the side thickness.

 

So actually seems like 200 ml is a legitimate representation of that bowl's useful capacity..

 

Consider aquariums are sold by the volume of the box the aquarium comes in, assuming aquariums came in boxes. So a 50 gallon aquarium does not hold 50 gallons, it displaces 50 gallons.

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32 minutes ago, Marshal Mo Hare, SASS #45984 said:

Nothing says what’s its volume better than filling it with water and measuring. I bet the bottom takes up a lot of what would be its volume.

Yep...Fill it with water, than pour into measuring cup...Read the amount....Make life easy....After that, who cares....

 

Texas Lizard

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Using a clear bowl as an example so you cab see the shape of the inside...a possibility? :blush:

 

image.png.b018d4c84444ea8a480dd7a9456b932a.png

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