Calculating SCUBA Depth with Exhaled Air and Terminal Velocity

[Dr. Surgery]

So if you were scuba diving and your depth gauge broke, could you create a system where you exhale some air and record the time it took to reach the surface. If so, what would they equation look like?

 

[berkeman]

So if you were scuba diving and your depth gauge broke, could you create a system where you exhale some air and record the time it took to reach the surface. If so, what would they equation look like?

Fun question. But first of all, when I'm scuba diving, it's hard for me to see my bubbles all the way to the surface. And second of all, we prefer for posters to show some effort in their questions -- what have you found in your reading about this question?

 

[nasu]

Maybe the size of the bubbles may be a rough indicator of the depth.
Have you observed a difference in the average size as you go deeper?

 

[Dr. Surgery]

While you may be able to observe the difference of the mass of the gas of the bubbles, wouldn´t the volume be the same because it is about how your lungs(Constant volume) will hold at a given depth/pressure, and I am not sure how reliable it would be to measure it. I am looking for an algorithm similar to dropping a rock, and counting how many seconds it takes for it to land to calculate how high a cliff is.

 

[berkeman]

I did a Google search on Bubbles Reach Terminal Velocity, and got lots of good hits. Here's a paper that may be helpful for you:

http://isites.harvard.edu/fs/docs/icb.topic1032465.files/Final%20Projects/Fluids%20Drag/Terminal%20Velocity.pdf