Skip to main content

Martin Gardner, Jearl Walker, and Coffee Cooling

A note for all you nerds out there---if you are looking for that famous article on coffee cooling, Martin Gardner mentions it but Jearl Walker analyzes it.

Perhaps a little background is in order. Does your coffee stay warmer longer when you add cream? This question isn't as dumb as it sounds. Yes, the cream cools it down, but Newton's Law of Cooling tells us that the rate of heat loss of a body is proportional to the temperature difference between the body and its surroundings. Adding cream reduces T - T_env so dQ/dt will be lower.

I clearly remember reading an detailed article on this topic in Scientific American back in the...well, let's say it was awhile ago. A graph, as I recall, compared theory and experiment. The article also discussed the effects of radiation---the change in color from black to white affects the energy radiated by the body.

But it was in The Amateur Scientist by Jearl Walker, not Martin Gardner's Mathematical Games. Several sources on the Web cite Mr. Gardner for this problem. They mention one of two books: The 2nd Scientific American Book of Mathematical Puzzles & Diversions or its reprint Origami, Eleusis, and the Soma Cuba. I bought both these books and I am here to report that they only give mention to the problem in the article "James Hugh Riley Shows, Inc."

I believe that this is the proper citation for Dr. Walker's article: The Amateur Scientist, Scientific American 237, 152 - 160 (1977). I haven't yet managed to obtain a copy but my search continues.

And why, you ask, do I care about this problem? Heat dissipation is a key problem for modern computers. You may have noticed your laptop warming up when you use it. That effect is peanuts compared to the heat generated by a data center that burns the electricity of a city of 50,000 people. Newton's Law of Cooling is a fundamental concept for computer system designers. And what better way to illustrate the concept, as Mr. Gardner and Dr. Walker so well knew, than with a cup of coffee?

Update:I reproduced Jearl Walker's coffee cooling experiment here.

Labels:

Comments

Post a Comment

Popular posts from this blog

Eating Around Georgia Tech: Ecco

Our Texas Instruments colleague Cathy Wicks was gracious enough to host several of us at Ecco tonight. This is one of those restaurants that has been on my list for a long time. Even though it is within easy walking distance of Georgia Tech, I hadn't made it there until tonight. The menu is a combination of Italian, Spanish, and French that make use of some local Georgia ingredients. The combination of those three countries is sometimes a little forced, although the georgia ingredients (fruit, cheese) were all great and perfectly appropriate. We started out with a meat and cheese board. This actually reverses the French tradition, where cheese usually follows the main course. Everything was excellent. The Georgia cheese was a big hit, as was the French cow/goat cheese. I thought the sauscisson was very subtle and very good. The waitress said that the roast pork pasta was their signature dish, so I had to try it. It had traditional broad pasta (fresh, of course) ...
Post a Comment
Read more

DCA: Cava Mezze Grill

Cava is a DC area chain with light Mediterranean food. Saibal encouraged me to try lunch at their airport location and I was very happy with the experience. I ordered falafel on SuperSalad with assorted other toppings. The falafel was tasty. The SuperSalad was light, flavorful, and very easy to eat. Overall, a healthy and enjoyable lunch, something you can't always say about airport eating.
Post a Comment
Read more

Pressure Cooker Candied Ginger

I made candied ginger a few years ago. It's not something I would do every day but I had a lot of fun doing it. I recently acquired a pressure cooker and it inspired an interesting idea to me: why not make candied ginger in the pressure cooker? It should be very soft and flavorful. Here is the result. I peeled two large ginger roots, cut them into small cubes, and put them in the pressure cooker with heavily sugared water. The traditional method first boils the ginger in plain water to soften it and then again in sugar water to candy it. The resulting candy was very tender but still with the characteristic ginger texture. It was also sweet without being overpowering. The traditional method leaves a lot of sugar crystallized around the ginger. The pressure cooker gives a much more subtle result. The ginger stays moist even after it cools but you can dry it in the oven at 350 degrees for about 10 minutes. That inspired me to dip it in chocolate. While I was in the b...
2 comments
Read more