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Getting wet in my leaky suit
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1,405 Posts
Discussion Starter #1
could anybody tell me:
the weights of fresh and salt water (in kg please)
how too calculate buoyancy
how too calculate the volume of water (at any temperature)


i have nothing else better too do =[ may as well keep the old noggin ticking over :)



cheers in advanced
 

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Registered
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2,140 Posts
The difference is in the volume.

Another way to think about it is this ... 1L of fresh water does not weight the same as 1L of seawater.

K.

i was sure there was a difference (albeit very small?)

due to the salt content? :)
 

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Well Balanced - Bitter and Twisted !!
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1,987 Posts
How will it keep your brain going if I tell you how to do it??

You have been expected to get an A+ gcse??

Water is 1 gram per cubic centimetre

Buoyancy is to do with the mass of an object and the amount of water it displaces .

Archimedes Eureka!!!

Next Google is your Friend.....
 

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Getting wet in my leaky suit
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1,405 Posts
Discussion Starter #9
How will it keep your brain going if I tell you how to do it??

You have been expected to get an A+ gcse??

Water is 1 gram per cubic centimetre

Buoyancy is to do with the mass of an object and the amount of water it displaces .

Archimedes Eureka!!!

Next Google is your Friend.....

because once i know those i can go do the harder questions on the internet :)

i understand the Archimedes principle

if the object displaces a higher density of water than itself it is positively buoyant ect
 

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No social integrator
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4,457 Posts
(P1 * V1) / T1 = (P2 * V2) / T2

P = Pressure in bar absolute. Sea level = 1 bar absolute
V = Volume in Litres
T = Temperature in Kelvin

Resultant Buoyancy = force upwards (displaced water) - force downwards (gravity)

Fresh water is 1 kg/litre
Sea water = 1.03 kg/litre (ish)

The rest you can work out for yourself :)
 

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Getting wet in my leaky suit
Joined
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1,405 Posts
Discussion Starter #12
(P1 * V1) / T1 = (P2 * V2) / T2

P = Pressure in bar absolute. Sea level = 1 bar absolute
V = Volume in Litres
T = Temperature in Kelvin

Reslutant Buoyancy = force upwards (displaced water) - force downwards (gravity)

Fresh water is 1 kg/litre
Sea water = 1.03 kg/litre (ish)

The rest you can work out for yourself :)
cheers :)

if you smell smoke... it'll be me ;)
 

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Getting wet in my leaky suit
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1,405 Posts
Discussion Starter #14
this is the combined *gas* law - doesn't work very well for liquids

Salt water weighs approx 8.55 lbs per gallon and fresh water weighs approx. 8.34 lbs per gallon

so now i can start doing lift bag physics ect??? :)



i need a job :sad:
 

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Hacked off member
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2,217 Posts
Density= mass/volume

Fresh water is less dense than salt water (because of the salt dissolved in the latter!) ie it has a lower density. This makes you more buoyant in salt water since a given volume of salt water can support a greater weight of you than the same volume of fresh water.




P1 V1 /T1 = P2 V2 /T2 is the combined gas law

P1 V1 = P2 V2 is Boyle's Law (applying to an ideal gas at constant temperature)
 

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aka,,, Tom Thompson
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3,626 Posts
beg borrow or steal a copy of the dm course work , it will explain most of what you want , in prob enough detail . encyclopedia of diving isnt bad , and the course workbook is usefull. without going to the expense of actually doing the course.
or
do the course.
 

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No social integrator
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4,457 Posts
this is the combined *gas* law - doesn't work very well for liquids
But is sometimes useful in buoyancy problems involving lift bags...

Admittedly including temperature could be considered overkill.
 

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No social integrator
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4,457 Posts
beg borrow or steal a copy of the dm course work , it will explain most of what you want , in prob enough detail . encyclopedia of diving isnt bad , and the course workbook is usefull. without going to the expense of actually doing the course.
or
do the course.
The PADI Encyclopedia of Recreational Diving is a brilliant book.
 
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