dive physics

[hammerheads]

Okay didnt mean to offend i was merely trying to show the formulas in action so the guy could see it visually as sometimes it helps.

Yes I know about the saltwater, freshwater formulas published inside the front cover of the DM exams and IDC Theory Exams and should have explained this more fully, my apologies for this.

[mjgreen]

Okay didnt mean to offend i was merely trying to show the formulas in action so the guy could see it visually as sometimes it helps.

Yes I know about the saltwater, freshwater formulas published inside the front cover of the DM exams and IDC Theory Exams and should have explained this more fully, my apologies for this.

doesn't offend me, just trying to help

[cave_troll]

your Depth gauge is actually a Pressure Gauge. when you look at it underwater it is convenient to have a depth instead of a pressure. - Its easier for most people to read a gauge that says 10m rather than 2x10E5 N/m

Now unless you recalibrate that gauge between a salt and fresh water dive, a reading on your gauge will be different to a tape measure. yes "10m" in salt water is slightly shallower than "10m" in fresh. HOWEVER we don't actually care about the depth, its the pressure and its effects on our body that we care about.
so if your SPG reads "10m" you're at the same pressure in salt or fresh water and the volume in your collapsable bottole will be the same.

So a question along the lines of "if you fill a collapsable container with 1 L of air at the surface and take it to 10m depth in salt and then fresh water, what is the difference in volume at 10m between salt and fresh water?" will depend on if you're using an depth gauge or a tape measure to measure depth

[mjgreen]

your SPG is a Sumersible Pressure Gauge. when you look at it underwater it is convenient to have a depth instead of a pressure. - Its easier for most people to read a gauge that says 10m rather than 2x10E5 N/m

Now unless you recalibrate that gauge between a salt and fresh water dive, a reading on your SPG will be different to a tape measure. yes "10m" in salt water is slightly shallower than "10m" in fresh. HOWEVER we don't actually care about the depth, its the pressure and its effects on our body that we care about.
so if your SPG reads "10m" you're at the same pressure in salt or fresh water and the volume in your collapsable bottole will be the same.

So a question along the lines of "if you fill a collapsable container with 1 L of air at the surface and take it to 10m depth in salt and then fresh water, what is the difference in volume at 10m between salt and fresh water?" will depend on if you're using an SPG or a tape measure to measure depth

That may be well & true, but since he specifically asked about DM, which uses the constants given and just says 10m (thus actual depth)

[nigelH]

Sumersible Pressure Gauge to read your depth?

And there was me thinking the SPG was the thing that read your tank pressure.
Well you live and learn....

[mjgreen]

Sumersible Pressure Gauge to read your depth?

And there was me thinking the SPG was the thing that read your tank pressure.
Well you live and learn....

Haha. I didn't spot that.

[cave_troll]

Sumersible Pressure Gauge to read your depth?

And there was me thinking the SPG was the thing that read your tank pressure.
Well you live and learn....

what the hell was i thinking of
now i've sorted my english i think my physics still stand up :-)

infact even a freshwater lake will give different results from a tank of distilled dionised water at STP

[mjgreen]

even a freshwater lake will give different results from a tank of distilled dionised water at STP

Do you often dive in a tank of distilled deionised water?

[A. Berk]

Finally, what's the definition of Coles Law?

Cole's Law states; "At any given pressure or temperature the amount of shredded cabbage/carrot gloop slapped on one's plate is directly proportional to how much space is left next to one's shrivelled steak"

oreBk