Hacker News Reader

Comment by skh | Hacker News Reader

Sphere's have surface area and volume. Neither of those quantities is given by the formula for the area of a circle. I’m not a physicist and can’t speak to the merits of the rest of your post but this error of yours makes me doubt your post's veracity. Did you make a mistake in your parenthetical remark? Maybe it edit if you have.

View on HN

I assumed it was a reference to the surface area of a sphere - which is 4pir^2. The point would still hold.

Makes sense. That’s what I would have thought if not for the area of a sphere in three dimensions remark.

Area = surface area not volume.

Physicists tend to drop constant factors when they do calculations, I’ve noticed.

A sphere has surface area and volume. I didn’t claim or imply that I thought area meant volume. It does not have area and the formula for the surface area of a sphere is not pi r^2. I mentioned this in my original post. Then there is the remark that whatshisface made: A = pi r^2, the area of a sphere in three dimensions. That is wrong and most likely a mistake.

When talking about dropping a constant factor are you referring to the 1/r^2 part or dropping a 4 in the statement A=pi r^2. Because if the latter then why keep pi? That’s a constant.

The constants perfectly divide out in this case, adding the pi was an afterthought so that people would recognize it as an area. Yes... It should have had a 4 as well. Too late to edit now.

Reply on news.ycombinator.com