Diving Physics Puzzle

[fppf]

Actually, it does, go try it

 

[ishmaelcat]

Thal & Tiger and fppf are all correct.

If you doubt fppf's point about actual balloons and don't want to go through the trouble of doing the exp. he suggests just think about how when you blow up a balloon the hardest part is getting it started -- the bigger it gets the easier it is to blow into it.

I do suspect however, that for the purposes of a classroom question, we are supposed to assume that the elastic is linear, just like the "perfect" springs we learn about in HS physics where F equals precisely -kx.

 

[Thalassamania]

I guess I don't understand what the "puzzle" is. It's rather a straightforward question with a rather straightforward answer if you grant the simplifying assumptions concerning balloon mechanics.

 

[Tigerman]

I guess I don't understand what the "puzzle" is. It's rather a straightforward question with a rather straightforward answer if you grant the simplifying assumptions concerning balloon mechanics.

Yeah, which is why my first answer.. Untill I realized ballons are weird things.
I do suspect the question dont take the weirdness of the balloon into account

 

[Thalassamania]

Yeah, which is why my first answer.. Untill I realized ballons are weird things.
I do suspect the question dont take the weirdness of the balloon into account

So what's the real question? Left half the gas out, keep the total pressure the same - no change. Mix in an equal quantity of another mixture of gases - average the values.

 

[tarponchik]

Thal & Tiger and fppf are all correct.

If you doubt fppf's point about actual balloons and don't want to go through the trouble of doing the exp. he suggests just think about how when you blow up a balloon the hardest part is getting it started -- the bigger it gets the easier it is to blow into it.

This is true, but for a different reason. When you just start inflating the baloon, your single breath makes 100% of the baloon's volume change and that is when the elastic is stretched the most. When you are doing your 10th breath you only add 10% more of air and the extra stretch of the elastic is almost negligible. The presure builds up, but it does that slowing down, on a log scale. Instead of comparing the difficulties of inflating, try to pop a fully inflated baloon and a similar baloon with only one breath in it. Whichever ballon boomed louder had the air at higher pressure.