Arrow-right Camera
The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Planet Rock Doc: Scientifically speaking: Stay cool

E. Kirsten Peters

Hot enough for you? I’ve been thinking about heat lately, and not just because of the torrid weather affecting much of the nation.

We all can easily verify that hot air rises – when you change a light bulb near the ceiling of your living room, you find the air up there is warmer than it is near the floor.

Early scientists tried to understand the basic facts of heat with general theories. One such theory stated that heat was something like a fluid. After all, it seemed that it could flow from warm bodies into cold ones, equalizing over time so that both were the same temperature. It sometimes affects the size of the bodies it inhabits, for example hot air takes up more volume than cold air – creating the reason that hot air rises.

But heat is an odd substance in some ways. It has no mass, a fact verified by weighing a solid object, then heating it up, and finding it still weighed the same.

Benjamin Thompson was an early scientist who studied heat. Born in 1753 in Massachusetts, he later moved to continental Europe where he was ultimately named Count Rumford in recognition of his scientific accomplishments.

Count Rumford is famous for a heat experiment. Back in his day, it was known that boring (grinding) out cannons made for a great deal of heat. Rumford immersed a cannon in a water bath, then ground out the hole as he measured the rise in temperature of the water. The change was so great the water actually boiled after two and a half hours of the heavy work. Rumford argued that the heat wasn’t a fluid at all, but something quite different that had been created by the vigorous motion of the grinding.

Rumford’s work revived a theory of heat that had been put forward much earlier by Francis Bacon. As Bacon had put it, the “very essence of heat is motion and nothing less.”

Bacon’s idea that heat was motion started to gain more adherents after Rumford’s work with the cannon. It fell to a man named James Prescott Joule to show that work of any kind can be transformed into heat. That included mechanical work – like grinding out a cannon hole – or chemical work or electrical work. When heat became recognized as something that could be equated to work, the modern science of energy began to come into focus and the unit of energy we call a “joule” was not far off.

You’ll be an example of energy relationships today as you go about your daily life. You’ll take in chemical energy from food. You’ll also burn enough energy to do all the basics of keeping your body functioning.

Exercise can lead to significant energy expenditure. A gentle walk will use 150 to 300 calories per hour, while running or shooting some hoops can burn 500 to 700 calories per hour.

Best wishes managing your personal energy balance today. And keep as cool as you can.

E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. Planet Rock Doc, a collection of Peters’ columns, is available at bookstores or from the publisher at wsupress.wsu.edu or (800) 354-7360. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.