Volume & Density at surface ?

[victorzamora]

How do you come up with the 1L of volume ?

Algebra. 4L*1ata=4ata*XL. When you do the math, you just solve for X. (4*1)/4=X Liters. You have a 1L balloon at 4ata that was 4L at the surface (1ata)

On this statement and according to my example what is the mass so i can divided by 4 ? and the volumes is ? so mass/4 * volume ? Sorry, sorry i got lost here...

You don't need the mass, because it stays constant. It requires merging equations, and is something not easily done on the computer. But, I'll try:
density1=m/V1 and density2=m/V2. mass is constant, so m=V1*d1=V2*d2. and then the masses drop out completely. You're just looking for RELATIVE densities. The volume2 is 4x what it was at 99ft(30m), so your density2 is 4x lower, or 1/4 of what it was.

 

[namerg]

Got it amigo..I feel stupido..

 

[victorzamora]

Got it amigo..I feel stupido..

No need....it's goofy the first while you look at it. It wasn't until I was doing deco-theory research that all the math started to click properly.....and I'm a rocket scientist

 

[namerg]

Jajaja Oh my god A rocket scientist and a diver. Holy bananas...my respects.

 

[TSandM]

Pressure and volume are reciprocals. If the pressure goes up, the volume goes down. Since the only way the volume can go down, if the same mass is present, is for the molecules to be packed more closely together, the density goes up. (This is all assuming a non-rigid container, something that can collapse and expand.).

So if the pressure doubles, the volume gets cut in half, and the density has to double because you have the same number of molecules packed into half the space. On the other hand, if you have 1L at 4ATA (33m) and you take it to the surface, the pressure there is 1ATA, so the pressure is one-fourth of where you started. So volume quadruples (4l) and density is cut to one-fourth the original, because now the molecules have tons of room to wiggle around.

I find that converting depth to ATA makes this trivial to visualize, and since you are operating in metric, converting to ATAs is dead simple.

 

[gopbroek]

No reason to fill stupid, these type of questions are great for everyone involved. This is basic knowledge that all divers learn but without thinking about it, it dims with time. By talking about it the information gets drawn back up front and for many, such as myself, an 'oh yes, now I remember this' moment occurs.