Unutterably Silly Quiz

[Shayne Parkinson]

That's interesting, Natasha! It does fit the question quite nicely, but it's not the one I was thinking of. I'll see if anyone gets closer...

[Shayne Parkinson]

Very nice, Javed! Still not the one I was thinking of, but the alternatives are perhaps more interesting.

One more hint: which freezes faster, hot water or cold?

[Javed]

Mpemba effect! When hot water freezes faster than cold water.

Explanation of this:

Spoiler:

Theories for the Mpemba effect have included:
* faster evaporation of hot water, which reduces the volume left to freeze
* formation of a frost layer on cold water, insulating it
* different concentrations of solutes such as carbon dioxide, which is driven off when the water is heated

The problem is that the effect does not always appear, and cold water often freezes faster than hot water.

Radiation safety officer with the State University of New York, James Brownridge, has been studying the effect in his spare time for the last decade, carrying out hundreds of experiments, and now says he has evidence that supercooling is involved. Brownridge said he found water usually supercools at 0°C and only begins freezing below this temperature. The freezing point is governed by impurities in the water that seed ice crystal formation. Impurities such as dust, bacteria, and dissolved salts all have a characteristic nucleation temperature, and when several are present the freezing point is determined by the one with the highest nucleation temperature.

In his experiments, Brownridge took two water samples at the same temperature and placed them in a freezer. He found that one would usually freeze before the other, presumably because of a slightly different mix of impurities. He then removed the samples from the freezer, warmed one to room temperature and the other to 80°C and then froze them again. The results were that if the difference in freezing point was at least 5°C, the one with the highest freezing point always froze before the other if it was heated to 80°C and then re-frozen.

Brownridge said the hot water cools faster because of the bigger difference in temperature between the water and the freezer, and this helps it reach its freezing point before the cold water reaches its natural freezing point, which is at least 5°C lower. He also said all the conditions must be controlled, such as the location of the samples in the freezer, and the type of container, which he said other researchers had not done.

The effect now known as the Mpemba effect was first noted in the 4th century BC by Aristotle, and many scientists have noted the same phenomenon in the centuries since Aristotle’s time. It was dubbed the Mpemba effect in the 1960s when schoolboy Erasto Mpemba from Tanzania claimed in his science class that ice cream would freeze faster if it was heated first before being put in the freezer. The laughter ended only when a school inspector tried the experiment himself and vindicated him.

(source)

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[Shayne Parkinson]

We have a winner! Take it away, Javed.

[Javed]

Thank you.

New Quiz:
I am a three digit number. My tens digit is five more than my ones digit. My hundreds digit is eight less than my tens digit. What number am I?

[natasha_fawn]

Originally Posted by Javed

Thank you.

New Quiz:
I am a three digit number. My tens digit is five more than my ones digit. My hundreds digit is eight less than my tens digit. What number am I?

194

(Message was too short.)

[Javed]

Correct!

[natasha_fawn]

Alrighty then.

There are only two species of primate that can normally have blue eyes. What are they?

[poohbear_nc]

male & female homo sapiens?

[Bilbo1967]

Originally Posted by poohbear_nc

male & female homo sapiens?

Males and females are different species? That would explain a lot!

I believe that I saw this on a David Attenborough thing; is it humans and lemurs?

[poohbear_nc]

Originally Posted by Bilbo1967

Males and females are different species? That would explain a lot!

I believe that I saw this on a David Attenborough thing; is it humans and lemurs?

It's always explained everything to me!

[Stitchawl]

Awww... I woke up too late to grab this one! I think Bilbo got it right.


Stitchawl

[poohbear_nc]

Indeedly!

[natasha_fawn]

Yep.

Specifically, humans and blue-eyed black lemurs. (Which are themselves a subspecies of black lemurs.) Darn, I thought that one would be a little harder. You're up, Bilbo.

[Javed]

Some interesting questions! Well done, Bilbo.