Because I've been swamped at work, and the book's due back at the library, I blew through "Why Things Break." It was a page turner, literally and figuratively, covering topics like the history of Pyrex, why the Titanic's hull failed so spectacularly, and the engineering of Cassini's power system. (History buffs may recall the predictions of doom.) As much as I enjoyed it, the highlight of the book was a scribbling about thermodynamics in the margin on page 200:
The "zeroeth" law of thermodynamics relates the concept of equilibrium. If you bring into physical contact two objects that are initially at different temperatures, they will eventually achieve a balance as heat is transferred. For example, if your coffee's too hot, you can plop in an ice cube. The ice cube turns to water as the coffee gradually cools down. I find it more fun to think of this as "how much more pleasant my spouse's ice cold feet feel after I've warmed them up." The amount of heat transferred is proportional to the temperature difference between the objects times the heat capacity of the object. ΔQ = ΔT * c
In "The PTA Disbands!" episode of The Simpsons, Lisa builds a perpetual motion machine. After seeing the machine, her father, Homer, yells at her: "…in this house we obey the laws of thermodynamics!" A machine producing more energy in the form of work than is supplied to it in the form of heat would violate the first law of thermodynamics. A machine that would completely convert heat from a warm body into work, without letting any heat flow into a cooler body, would violate the second law of thermodynamics, and is known as a perpetual-motion machine of the second kind. This is the more valuable type. There were a number of early attempts to design and construct perpetual-motion machines; however, since the 19th century, when the laws of thermodynamics became understood, most such attempts have been abandoned. It's now one of the quickest ways to have a patent rejected.
Another way to look at this:
Some background...
- You can't win; you can only break even.
- You can only break even at absolute zero.
- You can't reach absolute zero.
The "zeroeth" law of thermodynamics relates the concept of equilibrium. If you bring into physical contact two objects that are initially at different temperatures, they will eventually achieve a balance as heat is transferred. For example, if your coffee's too hot, you can plop in an ice cube. The ice cube turns to water as the coffee gradually cools down. I find it more fun to think of this as "how much more pleasant my spouse's ice cold feet feel after I've warmed them up." The amount of heat transferred is proportional to the temperature difference between the objects times the heat capacity of the object. ΔQ = ΔT * c
"You can't win, you can only break even."The first law of thermodynamics is known as the law of conservation of energy, that is the energy in the universe can't be created or destroyed, it can only change forms. For example, a guy falling off a ladder converts his potential energy into kinetic energy ... and a broken leg.
"You can only break even at absolute zero."The second law is more subtle: energy spreads out and disperses rather than staying concentrated. For example, if I run over a piece of glass, the extra dense air in my tires is very likely to come out. The opposite could also happen, but it's very, very unlikely. :-)
In "The PTA Disbands!" episode of The Simpsons, Lisa builds a perpetual motion machine. After seeing the machine, her father, Homer, yells at her: "…in this house we obey the laws of thermodynamics!" A machine producing more energy in the form of work than is supplied to it in the form of heat would violate the first law of thermodynamics. A machine that would completely convert heat from a warm body into work, without letting any heat flow into a cooler body, would violate the second law of thermodynamics, and is known as a perpetual-motion machine of the second kind. This is the more valuable type. There were a number of early attempts to design and construct perpetual-motion machines; however, since the 19th century, when the laws of thermodynamics became understood, most such attempts have been abandoned. It's now one of the quickest ways to have a patent rejected.
"You can't reach absolute zero."Aboslute zero is the temperature at which atomic activity is minimized. Although scientists have gotten close in the lab, observing some interesting behavior.like super-fluidity and, of course, bargains at ebay, absolute zero is believed to be unattainable, as is the speed of light or the miracle weight loss pill with no dangerous side effects. (Also available on eBay!)
Another way to look at this:
- You can't win.
- You can't break even.
- You can't quit the game.
Second law of thermodynamics bumper sticker: S happens
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