Ok serious question for anyone with any physics knowledge.

[mainegreen]

I was thinking about this while giving my kid a bath tonight. We were making a lot of waves in the tub, and pretending to play 'submarine' with the duplo blocks. (For those who may not know, Duplo is double sized legos.) I was thinking about the blocks and the waves, and I seemed to remember way back from the dark recesses of the last time I took physics that the pressure in water is equal to the depth in the water column it is, even if not directly below the top of the water column, in an upward bending part of pipe that dead ends, but below the highest point of water in the system. But waves, they're kinda funky aren't they? Do you measure pressure from the top of the nearest high wave? That can't be right. Does the pressure rise and fall at point x, as waves roll across it? Or does it stay constant as the waves pass? It seems to me that if you were to graph the pressure lines below waves, that you would have further waves, with the pressure lines flattening as you increase in depth. But that seems to violate what I seem to remember as being the water pressure rule. Is that rule more of a guideline, like Newtonian physics, that really must be chucked in more complex environments?

For realz, I was wondering about this at bath time tonight.

Is this question to ridiculous for Wednesday night in the lounge?

[The Straight Story]

1. Will try it with my vodka and get back to you

what was the question again?

[mainegreen]

3. Excellent. But do you have enough vodka to run a decent test?

sounds expensive to fill a tank with vodka. And do you have pressure gear too?

:D

[The Straight Story]

4. Enough vodka...always :) And on baths and physics

I pondered many same things when giving my kids baths. Funny isn't it? As I kid I was too busy playing in the tub (usually, not always) to ponder such things. As an adult I find myself looking at things in new ways (from blowing bubbles to watching water drain and thinking about it's speed/pressure/size of pipe, etc).

Next time i take a bath, I think I will drag in a bunch of testing gear with me. Just have to be careful not to plug it in....

[Sandrine for you]

5. For this one I got an answer....

Just a shooter and something with vibrations.

[mainegreen]

8. but does straight story have equipment sensitive enough for a shot glass?

[Sandrine for you]

18. It take me some times to understand. LOL

[Sandrine for you]

2. At this precise hour, it's just to complicate for me to simply get a answer to the second question,,

[krispos42]

6. I think it would be steady

The average of the wave height.


If you had an L-shaped pipe that was closed at the bottom and filled halfway up the top, then the pressure at the bottom right of the L is the same as at the bottom left, even though the bottom-right location doesn't have a column of water over it.

[mainegreen]

7. Wow.

steady. That almost seems crazy to me. But, still I guess it makes sense.
It would have to be, wouldn't it? Otherwise the wave couldn't be supported.

Hunh.

[krispos42]

9. The water is moving upo and down, so you might have some variation

due to momemtum being transferred to the pressure gauge.

:shrug:


It should be steady, though. Best guess.

[Pierre.Suave]

10. Here is what I think, having thought about this for a bit...

Yes, the pressure will change as the wave moves overhead, but, and this is a very big but, the wave is too small to make a measurable difference in the apparent pressure to all but the most sensitive detection gear. If the wave did make a marked difference, it would have to be massive as water pressure increases in atmospheres every 33 feet (if I remember correctly) This would then lead me to believe that, just like the water column rises and dips in relation to the mean, so would the pressure.

For example, if a wave passes that is 5 feet above sea level, then there is a dip 5 feet below sea level right behind it. The pressure would equal that, if it does indeed make a difference.


I doubt a wave in a bathtub would have any measurable effect at all.

[mainegreen]

11. Interesting. So then in essence, there must be a maximum given wave height allowed?

Given a set of atmosphere pressure and gravity conditions, then there is a maximum wave height allowed, before the wave top has a pressure equal to that of the atmospheric pressure. Since the wave keeps on decreasing in pressure.

Agh.

My head. Spinning.

[Pierre.Suave]

12. maybe,but I dont think so, on earth anyway

I dont think our atmospheric pressure is enough to restrict wave height given that waves are created by energy moving through the water, and have no direct relationship to atmospheric pressure, or gravity.

Plus, water is a unique molecule with all kinds of neat ability to bind together and seemingly defy gravity.

[mainegreen]

13. Hmmm. I need to find a physicist.

I have MORE questions.

x(

[Pierre.Suave]

14. Thats the problem...

once you start asking questions, you never actually get an answer, just more questions..

:P

[Jeff In Milwaukee]

15. You thought of this in the fucking bathtub?

I can't wait to hear what you thought of while doing the dishes...

[mainegreen]

16. I'm trying to think about what I normally think about while doing dishes.

I think, though, that it's along the lines of 'I hate dishes.'

:D

[Jeff In Milwaukee]

17. LOL

Paper plates. Screw the environment!