So I’m bad at math. Can you explain why we’ve decided to multiply pi by 2? Is there an articulable reason or is it just a rule?
c+x= pi * (d+2) in this case, right? So where did that multiply pi by 2 come from?
Comment on The Planet, some string and a bell.
towerful@programming.dev 8 months agoc = pi x d
So, to increase d by 2 meters (cause d = 2 x r), that’s 2 X pi, or 6.28 meters for string?
TheActualDevil@lemmy.world 8 months ago
reattach@lemmy.world 8 months ago
Distribute the pi on the right side of your equality, and replace c with pi*d:
c+x = pi*(d+2) pid+x = pid + pi2 x = pi2
To generalize for an height h, x = pi2h
TheActualDevil@lemmy.world 8 months ago
Oh, I see now. I missed some pretty basic math there with that distribution. That makes sense now, thank you!
PetDinosaurs@lemmy.world 8 months ago
Correct.
davidgro@lemmy.world 8 months ago
To really emphasize it, the same amount of extra string would be needed if it was instead wrapped around a small marble at first and the diameter expanded by the same amount.