Quiz - Physics - Volume at Surface

[Pedro Burrito]

From the Physics Section of the PADI Dive Theory Exam:

If a sealed, flexible, air filled container with a volume of one litre at 20m/66ft is released, what will its volume be when it reaches the surface (given that it doesn't explode)?

a. 1 litre

b. 2 litre

c. 3 litre

d. 4 litre


I will post a daily question from my exams to help newer divers and to encourage more experienced divers to interact gracefully and helpfully with the newer divers.

Reminder - this is a post in the Basic Forum and it is a green zone. Please be nice and on topic.

Thank you for your patience while we try to give people something to discuss other than Covid-19 and/or Politics. I will post the answer covered by the spoiler tag later today.

 

[-JD-]

Seriously, do these questions come frome the creator as stream of consiousness without review at a distance?

A balloon is "flexible"
An SMB is "flexible"
A fill whip hose is "flexible"

I would expect different results ...

ETA: No aspersions toward you @Pedro Burrito , I appreciate and enjoy what you are doing here.

 

[tridacna]

Seriously, do these questions come frome the creator as stream of consiousness without review at a distance?

A balloon is "flexible"
An SMB is "flexible"
A fill whip hose is "flexible"

I would expect different results ...

ETA: No aspersions toward you @Pedro Burrito , I appreciate and enjoy what you are doing here.

Yes but...I'm certain that we're checking to see if students understand Boyle's Law here. Who knows there may be a significant temp gradient between 0m and 20m. Let's just keep it simple.

 

[-JD-]

Yes but...I'm certain that we're checking to see if students understand Boyle's Law here. Who knows there may be a significant temp gradient between 0m and 20m. Let's just keep it simple.

Sigh... Words have meaning. I guess it is expecting too much for the ones that are actually relevant to the (assumed) question to be used.
"Elastic", "variable volume", "expandable", or some such.

That would be quite the thermocline to have a order-0 magnitude impact considering that we are talking about absolute temperatures.

ETA: Also, seems to presume that the "container" imparts no pressure of it own accord, regardless of volume.

Engineers should be locked away from things like this. Or at least Pedro should start posting these before he goes to bed, and I'll at least have a beer in me ...

 

[tursiops]

A balloon is "flexible"
An SMB is "flexible"
A fill whip hose is "flexible"

LOL! And you need to be more flexible! Hey, it's basic dive physics question. The only two containers are rigid or flexible.

 

[Steve_C]

I thought the same thing. The answer they are looking for is if a one litre bubble is released and it stays intact what will its volume be when it reaches the surface. Of course it will be different for any physical container. But the point is that the deeper the more air volume/pressure at the surface and that has to be dealt with.

flexible means bendable which is not wanted here. What is wanted is stretchable which is different.

 

[Angelo Farina]

Well, in this case I do not see big faults in the question. It is clear that the container is something which can freely expand, following the expansion of the gas contained in it. And it is sealed, not as my SMB which has an opening at the bottom. And it is not exploding. So the answer is univocal...

 

[-JD-]

LOL! And you need to be more flexible! Hey, it's basic dive physics question. The only two containers are rigid or flexible.

Hence the "beer" component in my last comments ...

BTW, do we not need to understand that hydros test the expansion and elasticity of our dive cylinders??? Does it mean that they are flexible?
And that implies the other part of my comment - about engineers being locked away from questions like this.

 

[Pedro Burrito]

Spoiler: Answer

c. 3 litre

 

[TMHeimer]

LOL! And you need to be more flexible! Hey, it's basic dive physics question. The only two containers are rigid or flexible.

Yes. It's a simple test for people like me. IT MUST be a balloon. It's ALWAYS a balloon.....I saw that in the pictures in the manual.