It’s Hot!

The “authorities” have finally granted me the privilege of drinking coffee. (It’s limited to only one small decaf cup a week, but I’ll take it.) I am very particular about how I make it. I add first a spoonful of decaf instant coffee to a ceramic mug, then freshly boiled water, then a spoonful of sugar. Finally, I top it off with a drop of cream.

Since I stared handling boiling water and warm mugs myself, I noticed that some parts of the mug feel hotter than others.  Since all the hot water coming out of the kettle is more or less at the same temperature, what happens to it once it’s poured into the the mug?  What is the temperature distribution there?

I decided to conduct an experiment to find out.

1. My hypothesis was that the water at the top of the cup would be hotter. I thought this because I know that hot air rises and cold air sinks.  My mom and dad were mixed in their opinions.  My dad said that even though he agreed with me, one could also argue that the water at the bottom would be warmer because it was insulated by  three sides, verses the top water, which was exposed to cooling evaporation. 
2. I started the experiment by boiling a kettle of water. Then, I poured it into a heat-proof glass.  I used an infrared thermometer to measure the temperature on the bottom, middle, and top of the cup.  These are the results that I got:
   
   

   Measurement	Set 1 (C)	Set 2 (C)
   Top	82.1	79.3
   Middle	80.1	78.0
   Bottom	71.3	72.1

   
   
3. The experiment confirmed my hypothesis.  The water got hotter as we moved from the bottom to the top.
4. After I finished my experiment, I repeated it again (Set 2) to make sure that I would get consistent results. 

So there you have it! If you ever wondered where the best place for holding a hot cup is, it is by its handle, of course. But if it doesn't have a handle, try empting some of the hot liquid and grabbing it by the glass on top where there is no liquid (the temperature there was 20 degrees lower). If you can’t do that, then definitely go for the base.

For more thoughts on the proper upbringing of young ladies, hot coffee, and the futility of parental restrictions on drinking it, check out Johann Sebastian Bach’s Coffee Cantata (translation from the German and a short musical excerpt below).  First performed by Bach at the Zimmerman's Coffee House, in Leipzip, in 1732.




Narrator
Be quiet, stop chattering,
and pay attention to what's taking place:
here comes Herr Schlendrian
with his daughter Lieschen;
he's growling like a bear.
Hear for yourselves, what she has done to him
Schlendrian
Don't one's children cause one
endless trials & tribulations!
What I say each day
to my daughter Lieschen
falls on stony ground.
Schlendrian
You wicked child, you disobedient girl,
oh! when will I get my way;
give up coffee!
Lieschen Father, don't be so severe!
If I can't drink
my bowl of coffee three times daily,
then in my torment I will shrivel up
like a piece of roast goat.
Lieschen Mm! how sweet the coffee tastes,
more delicious than a thousand kisses,
mellower than muscatel wine.
Coffee, coffee I must have,
and if someone wishes to give me a treat,
ah, then pour me out some coffee!
Schlendrian If you don't give up drinking coffee
then you shall not go to any wedding
feast, nor go out walking. oh! when
will I get my way; give up coffee!
Lieschen Oh well!
Just leave me my coffee!
Schlendrian Now I've got the little minx!
I won't get you a whalebone skirt
in the latest fashion.
Lieschen I can easily live with that.
Schlendrian You're not to stand at the window
and watch people pass by!
Lieschen That as well, only I beg of you,
leave me my coffee!
Schlendrian Furthermore, you shan't be getting
any silver or gold ribbon
for your bonnet from me!
Lieschen Yes, yes! only leave me to my pleasure!
Schlendrian You disobedient Lieschen you,
so you go along with it all!
Schlendrian Hard-hearted girls
are not so easily won over.
Yet if one finds their weak spot,
ah! then one comes away successful
Schlendrian Now take heed what your father says!
Lieschen In everything but the coffee.
Schlendrian Well then, you'll have to resign yourself
to never taking a husband.
Lieschen Oh yes! Father, a husband!
Schlendrian
I swear it won't happen.
Lieschen Until I can forgo coffee?
From now on, coffee, remain forever untouched!
Father, listen, I won't drink any
Schlendrian Then you shall have a husband at last!
Lieschen Today even dear father, see to it!
Oh, a husband! Really, that suits me splendidly!
If it could only happen soon.
Narrator Old Schlendrian goes off to see if he can find a husband forthwith for his daughter Lieschen; but Lieschen secretly lets it be known: no suitor is to come to my house unless he promises me,and it is also written into the marriage contract,that I will be permitted to make myself coffee whenever I want.

Narrator, Lieschen, Schlendrian A cat won't stop from catching mice,
and maidens remain faithful to their coffee.
The mother holds her coffee dear,
the grandmother drank it also,
who can thus rebuke the daughters!