Simviation Forum - how water reacts to differnet situations in 0 g's

Dec 28^th, 2008 at 6:37am

T1MT1M Offline
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http://www.spikedhumor.com/articles/170937/Water-in-Space.html

Pretty interesting

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Reply #1 - Dec 28^th, 2008 at 8:00am

Steve M Offline
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Cool, it would be fun to swim through one of those.

Flying with twins is a lot of fun..

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Reply #2 - Dec 28^th, 2008 at 9:07am

T1MT1M Offline
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you would need a lot of water because every time you pulled through the water to propell yourself forward all of the water would go in the other direction Cheesy

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Reply #3 - Dec 28^th, 2008 at 11:31am

skoker Offline
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You can never swim in that because of newtons laws.

« Last Edit: Dec 29^th, 2008 at 1:35pm by skoker »

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Reply #4 - Dec 28^th, 2008 at 11:38am

Fozzer Offline
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skoker wrote on Dec 28^th, 2008 at 11:31am:

You can never swim in that because of neutons laws.

neutons....neutrons...Newtons... Wink

...!

...it's Snot, under a Microscope!... Shocked

...!

F.... Wink

...!

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Reply #5 - Dec 28^th, 2008 at 11:51am

87HondaShadow Offline
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I like that one with the water drops inside a bubble thats inside a sphere.

Err 30kb limit?

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Reply #6 - Dec 29^th, 2008 at 1:00am

T1MT1M Offline
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skoker wrote on Dec 28^th, 2008 at 11:31am:

You can never swim in that because of neutons laws.

Newtons*

I was thinking if you had a large enough body of water in space then you could get some momentum and go straight into it in a streamlined position. Yes the whole body of water would move in the same direction as you at first but then as you swam around in it then the water would move in the opposite direction to you.

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Reply #7 - Dec 29^th, 2008 at 2:00am

Mushroom_Farmer Offline
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Fozzer wrote on Dec 28^th, 2008 at 11:38am:

skoker wrote on Dec 28^th, 2008 at 11:31am:

You can never swim in that because of neutons laws.

neutons....neutrons...Newtons... Wink

...!

...it's Snot, under a Microscope!... Shocked

...!

F.... Wink

...!

In the 80s, much like Dr. Strangelove, I learned to love neutrons. Grin

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Reply #8 - Dec 29^th, 2008 at 2:09am

a1 Offline
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That is just awesome.

Oh how amazing the hydrogen bonds get demonstrated. I love things that are weightless.

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Reply #9 - Dec 29^th, 2008 at 1:31pm

PerrierBaroudeur Offline
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Newton's laws wouldn't prevent you from swimming in one of those water spheres... not in the least. I don't see where that came from.

Think of it in terms of the physics involved:

In order to swim, a person exerts a force by pushing their hand / foot in the opposite of the direction they want to go. According to Newton's Third Law, the force exerted by the swimmer's hand / foot against the water must equal the force exerted by the water against the swimmer's hand / foot.
So, F_{hand on water} = F_{water on hand}

Force is equal to mass multiplied by acceleration, according to Newton's second law.
So, F_{hand on water} = m_hand * a_hand
And F_{water on hand} = m_water * a_water

Those two quantities must be equal, as previously stated.
So, m_hand * a_hand = m_water * a_water

Assuming that the water sphere is actually big enough for a person to swim in (a fair assumption, I think), then the mass of the water will be greater than the mass of the human.

But, the two forces still must equal one another, despite the disparity between the two masses. Looking at the equation, it becomes clear that the water's larger mass must accelerate more slowly than the hand's smaller mass.
Thus, a_hand > a_water

What this means is that a person could indeed swim around inside one of those water spheres; because the acceleration of the person will always be larger than the acceleration of the water sphere, the person will never have to worry that the water will "escape", because the person will always propel himself faster than he propels the water backwards. Sure, swimming in a straight line, you'd reach the edge of the water sphere, but that's no different from reaching the edge of a swimming pool Wink

Note: Following vector rules, F_{hand on water} = F_{water on hand} should read F_{hand on water} = -F_{water on hand}. However, the negative sign merely denotates direction, so I left it off above. The magnitudes of the forces are indeed the same.

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Reply #10 - Dec 29^th, 2008 at 1:58pm

Steve M Offline
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That is just an amazing description! I love physics. And I almost was going say if I can't swim in it, I'll get in it and throw space tools. Wink

Flying with twins is a lot of fun..

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Reply #11 - Dec 29^th, 2008 at 2:20pm

T1MT1M Offline
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It would be really weird come to think of it of swimming in space because the concept of "sinking" would no longer be present. you would just hang there. Usually you float because of the air in your lungs but in space you can't float to the top. Also when you breath out your bubbles wouldn't go to the top they would also hang there with you in the bubble of water.

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