And yeah, I’ll take some razzing on this one, since I don’t remember the relevant math at this point in my life.
I was making a big batch of meatballs, with a recipe that stated yield as approximately 80 1.5" meatballs. I decided to make them smaller (about 1"), and got closer to 220. I would have expected around 120, working from the ratio of diameters, but can’t remember calculating volume well enough to figure out how I got the result I did.
The volume of a sphere is: (4/3) * (pi) * (radius CUBED)
The cubed part is what throws of both you and everyone else in this kind of situation. It means that if you increase the radius by only 50%, the new volume will be 270% larger.
270% of 80 is 216. I’m amazed at how close you got!
:). Not the most precise measurement, I admit (I was using a melon baller as a scoop), and I did see some minor size variance in the finished product. If the diameter you give would have gotten me the yield I did, then you’re probably right.
The fact that volumes scale as the cube of the diameter (or radius) gets quite interesting when you start looking at astronomical objects. For example, the diameter of the sun is about 110 times the diameter of the earth, which doesn’t seem all that much, until you consider that the volume of the sun is 110 ^ 3 = 1.3 million times the volume of the earth. In other words, pretty damn huge.
This is why giant animals in monster movies are unrealistic. If you take an animal (like an elephant, say) and enlarge it to twice the size (i.e. it’s twice as tall), it has eight times the volume (and is presumably eight times as heavy), which its legs, which have twice the length and four times the cross-sectional area as before, would be unable to support.
It was a timeline or something to show how the price of gas went up. At each date an illustration of a barrel was shown, in false 3-D. Well, when the price went by half, the same illustration was shown 1.5 times larger; by 100%, twice as large. All very pretty and understandable, I guess, but absurdly incorrect. Indeed, correct illustrations of the cube multiplication of volume would have been all the more informative (and dramatic, if you want to look at it that way).