Which is faster?

quattro

quattro

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Staff member
Easy one for getting your head around.

I have two identical blue bottles filled with water to within an inch of the top.

The internal diameter of the neck of the bottles is 19mm.

I place the bottles in temperature controlled rooms, Bottle A at 30F and Bottle B at 50F for a period of 12 hours to allow them to acclimatise.

Then I drop a small (10mm) ball bearing into each of the bottles at the same time - which one is faster to the bottom.

Richard
 
Hello Richard,

The viscosity of water increases with decreasing temperature. 30 degrees F is -1.11 degrees C. 50 degrees F is 10 degrees C. I don't have the viscosity of water below 0 degrees C, but at 0 degrees C water is 36.7% more viscous than water at 10 degrees C. Therefore given the resistance that the ball will experience to moving through the liquid being higher for the colder water, I would expect the time taken to reach the bottom of the bottle to exceed that of the ball in the warmer water.

Ron.
 
harveyP6 wrote,..
At 30 degrees F the water will be ice................
Click to expand...

Hello Harvey,

The size of the bottle was not given, so that assumption cannot be made. As an example, on a day when the temperature fails to climb above zero degrees C, water in puddles or in containers may contain ice deposits, hence the viscosity will be greater, while smaller quantities may be completely frozen depending on the prevailing conditions. Larger quantities however will not be.

Ron.
 
Oracle wrote,..
Is it important that the bottles are blue?
Click to expand...

Blue bottles float around in the water when you go for a swim at the beach and give you a sting if you happen to be unlucky...ouch!!... :LOL:

Ron.
 
SydneyRoverP6B said:
harveyP6 wrote,..
At 30 degrees F the water will be ice................
Click to expand...

Hello Harvey,

The size of the bottle was not given, so that assumption cannot be made. As an example, on a day when the temperature fails to climb above zero degrees C, water in puddles or in containers may contain ice deposits, hence the viscosity will be greater, while smaller quantities may be completely frozen depending on the prevailing conditions. Larger quantities however will not be.

Ron.
Click to expand...

The size of the bottle is immaterial as ice floats so will always be on the top preventing anything sinking through it 8)
 
Pacific ocean..lol....salt water...now that is different again,... :LOL:

If the water happens to be....."pure liquid water can be supercooled well below that temperature without freezing if the liquid is not mechanically disturbed. It can remain in a fluid state down to its homogeneous nucleation point of approximately 231 K (−42 °C)."

It could be pure liquid water in a blue bottle from the Pacific ocean....so many possibilities.... :)

Ron.
 
Well done Harvey 8)

The fact that they are blue, with 19mm necks and 10mm balls, are only there to make you think that you have to work it out, when you don't.

Do Red Herrings live in the Pacific?

Water starts to expand as it gets down to 4C as it is starting to set up its solid structure, so at 12 hours at below freezing, there will be at least a skin of ice.

Richard
 
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