Quiz time!
You have a torus (basically, a ring) made of steel. Consistent all the way around.
When you heat the torus, will the inner diameter....
(Note, metal expands when you heat it.)
Why does the inner diameter increase?
Well, a circular expansion is exponential.
Due to this, the metal in the inner circle, pushes harder to grow, than the outer diameter (and the metal in between).
When I first learned this, I was flabbergasted, but, if you think about it, it makes sense.
@Firesphere circumferences are the devils work. If you add 3 feet to a rope that goes around the ENTIRE planet, suddenly the whole rope is 6 inches off the ground. How the heck does that work without shenanigans (and Pi).
@amyherself @Firesphere I love that trick (well, fact or whatever, it's not like anyone had done it)
@PetraOleum @amyherself I did the math on that.... because... well... I had to :D
@amyherself I think Mark Rober did a video on that, but I can't find it :(
@Firesphere this is fiendish
@fincham It's science ;)
@Firesphere I thought about it without looking it up and I’m going to say that the inner diameter increases. I’m going to go look it up now and report back 😂
@Firesphere well Google seems confused about it but I’m gonna say it has to expand otherwise shrink fitting in engineering wouldn’t work very well
@Firesphere 
No way! Physics maaaan
@Firesphere I only knew the answer because I'd seen it demonstrated in class at high school
@PetraOleum I have demonstrated it in middle school in the Netherlands myself :) (I used to teach physics)
The answer is B, the inner diameter will increase.