Scientific questions answered enjoyably

 kw: book reviews, nonfiction, answers, science, humor

Want to know the easy way to convert between °F and °C? On page 192 of  What Einstein Didn't Know: Scientific Answers to Everyday Questions by Robert L. Wolke, he explains the 40-40 method as clearly as any I have seen. We just need to remember 2 things:

1. A Celsius degree is 1.8 (or 9/5) as big as a Fahrenheit degree.
2. -40°C = -40°F.

Because the meeting point of the two scales is -40, first shift the zero point by adding 40. Then, if it's °C, multiply by 1.8, and finish by subtracting 40. If you're starting with °F, divide instead of multiplying: add 40, divide by 1.8, and subtract 40. Examples:

• Starting with 68°F: 68+40 = 108. 108/1.8 = 60. 60–40 = 20°C.
• Starting with 40°C: 40+40 = 80. 80*1.8 = 144. 144–40 = 104°F.

To do it without a calculator, if you can multiply and divide in your head but find 1.8 a hard number to use, to multiply by 1.8, multiply instead by 9 and then divide by 5; to divide by 1.8, multiply by 5 and then divide by 9. It's easiest to do the multiplying first. It's even better if the result won't be in even degrees. For example, to convert 56°F, add 40 (=96), multiply by 5 (=480), divide by 9 (=53.33...), then subtract 40, to get 13.33...°C.

Dr. Wolke passed away last August at the age of 93. I suppose this book is his last legacy. He wrote a number of books in the same vein. He liked to write about "Kitchen Science." In this volume he confines The Kitchen to one chapter of 24 pages, including the answer to "How does a simmer differ from a slow boil?" (Quick answer: The bubbles in simmering water seldom make it to the surface, but their presence lets you know the temperature is the same. Simmering saves energy.)

When explaining chemical and chemico-physical processes he takes us right to the molecular or atomic level. Even below boiling, for example, some water escapes into the air because the temperature represents the average of a range of molecular speed, and the faster water molecules find it easier to escape the liquid water into the atmosphere. Boiling means we've added enough energy to raise all (or most) of the volume of the water in a pot to the boiling temperature, so more energy just goes into driving water molecules into the air. They gather into bubbles on their way up from the bottom of the pan, where the heat is being added.

I remember when kids could get a Chemistry Set for a birthday present. Just about everything in those sets is banned today. Even in Chemistry class in high school, I've been told the teacher does nearly all the experiments in front of class, wearing lots of safety gear, and the students hardly have any lab time. You just can't learn chemistry by watching it!

Here and there in the book we find bits called "Try It". They are safe little experiments anyone can do with little or no equipment. Here is one from page 124 (next to a discussion of sublimation, or the evaporation of ice directly without passing through a liquid stage):

Measure the length of a convenient icicle during a cold spell. Then come back in a few days and measure it again. Make sure the temperature hasn't gotten above freezing in the meantime, so that there hasn't been any melting. You will see that the icicle has gotten smaller by sublimation.

I my experience it takes only a day or two for a noticeable change to occur, even in very frigid weather. In addition to answering questions he has encountered during a long career as a professor of Chemistry, he has items here and there titled, "You didn't ask, but..." One is "Why won't a candle burn without a wick?" (p 50) The answer is based on the need to get some of the hot wax above the surface of the pool of melted wax, which would cool it too much to burn.

The author encourages us to browse or even hop about, and many readers may enjoy doing so. I am a straight-through kind of reader. Either way, it's a great introduction to many less-well-known subjects, and offers a new take on some better known ones.