Science fair Q

[ScubaSteve101]

Ive decided im going to do my science fair project on taking a balloon to a depth and inflating it, zip tieing it shut then ascending to see the affects on the size of the balloon. What depth do you think we will start being able to see a noticable diffrence (naked eye) on the size on the balloon.

 

[Gombessa]

Well, depending on the elasticity of the balloon, it seems like going from 33ft to 0ft should increase the size of the balloon by almost 2x, so that would seem sufficient to be noticeable to the naked eye.

 

[ScubaSteve101]

ok thanks thats where i will start because the quarry im planning on diving in drops down to about 50F at about 40

 

[Walter]

Steve, I have data from a similar project a young lady did several years ago. Send me a PM with your e-mail address and I'll share the data. Seeing how someone else approached this can't help but make your project even better. It also includes safety precautions she took to avoid getting injured while doing the experiment. I remember a woman who aspirated water about 20 years ago when she attempted to blow up a ballon at depth.

 

[langforg]

Why not inflate it at the surface and see how much smaller it gets at depth?

 

[Soggy_Diver]

This is similar to the challenge that we did on the deep dive for my AOW course, but in reverse. In teams, we inflated a balloon on the surface, took it down to 85 feet (happened to be the depth), measured the diameter with a string that had knots at 3 inch intervals, and multiplied the knots by 3 to convert the diameter to inches. The purpose, I think, was to see if we could work as a team a and solve a problem while narced.

The thing that made it tricky was that as well as shrinking as we descended, the balloon also stretched up toward the surface, so the neck was long and thin, and the top was more of a sphere. I wonder if holding the balloon in a mesh bag, or putting your hand on top, would keep the shape similar regardless of depth?

 

[Warthaug]

And idea that may overcome some of the issues others have mentioned, and which would be more quantitative then looking at the size of a balloon.

Go to a medical supply store and buy a large syringe (60ml or 100ml). "Fill" the syringe to the last volume mark with air (i.e. if using a 60ml syringe, pull back the plunger to the 60ml mark), and then plug the open end of the syringe with something airtight (silicone caulking maybe?). When you submerge the water pressure should push the plunger into the syringe, and you should be able to easily read the change in volume off of the syringe case.

You can also do all of the math, to make it more scientific. You can use Boyles law to calculate the exact pressure changes you are monitoring.

Bryan

 

[Ber Rabbit]

Go to a medical supply store and buy a large syringe (60ml or 100ml).
Bryan

If you can't find a medical supply store go to a farm supply store like Tractor Supply and get an oral syringe for large animals.
Ber :lilbunny: