Can Water Float on Water

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Can Water Float on Water

Postby ialv1265 » Tue Nov 13, 2012 6:26 pm

my daughter is working on a project - can water float on water? In the procedure, it tells us to flip one bottle on top of the other which is complicated. Do you think the results will be altered if we just pour the water from one bottle to another using a funnel?

Please advise.
ialv1265
 
Posts: 1
Joined: Sun Nov 04, 2012 7:01 pm
Occupation: Student - 5th grade
Project Question: My mom is helping me with my project does water float on water and we are having a hard time flipping the water from 1 bottle to the other using the laminated card. Is it ok if we just pour the water from one bottle to another and get the same results.
Project Due Date: Nov 16
Project Status: I am conducting my experiment

Re: Can Water Float on Water

Postby theborg » Thu Nov 15, 2012 3:18 pm

ialv1265,

Welcome to Science Buddies, and thank you for your question. I assume you are performing the following experiment:

http://www.sciencebuddies.org/science-f ... ml#summary

I looked into this project you and your daughter are doing. The short answer is yes, you will likely skew results.

The key mechanism you are trying to observe through this experiment is "Thermohaline Circulation". By doing the "flip" technique, the different liquid solutions (i.e. salty vs. fresh, cool vs. warm) are allowed to mix gently via a small interface area, thereby controlling the mixing variables to the maximum extent. "Pouring" one solution into the other via a funnel will likely cause rapid turbulent mixing to occur such that it would become the dominate mechanism by which the two solutions attempt to reach equilibrium. Any observations made while this turbulent mechanical mixing is occurring would be inconclusive with respect to any mixing (or lack of it) caused by density or temperature differences.

I agree the flip technique is rather tricky, but important. Keep practicing and I’m sure you guys will get it. For the reasons stated above, keep in mind to fill both bottles to up to the brim so there is as little space between the liquids when you remove the index card. The better you do this, the more you are literally placing a body of liquid on top of another body of liquid with minimal mixing due to that placement occurring (one of the variables you are trying to control).
I hope this helps.

theborg
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"As the circle of light increases, so does the circumference of darkness around it."
~ Albert Einstein
theborg
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Posts: 224
Joined: Mon Oct 03, 2011 12:26 pm
Occupation: US Air Force Space & Missile Operations
Project Question: "To explain all nature is too difficult a task for any one man. 'Tis much better to do a little with certainty and leave the rest for others that come after you, than to explain all things by conjecture without making sure of anything." - Sir Isaac Newton
Project Due Date: N/A
Project Status: Not applicable


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