Is this the truth? I want to know.
2006-11-13 11:45:12 · 5 answers · asked by American Splendor 5 in Science & Mathematics ➔ Other - Science
Teacher is wrong. This is a popular misconception, but the usually cited "proof", that old windows are thicker at the bottom, only proves that old glass was irregular in thickness. A smart glazier would install a pane thick edge down for better strength.
Evidence to the contrary includes the fact that large telescope mirrors and lenses, which must be figured to within less than 100 nanometers (4 micro-inches), maintain this figure indefinitely. Telescopes over 100 years old are still in use. Also, glass artifacts over 3000 years old still hold their shape.
This misconception arises because glass, being an amorphous, as opposed to crystalline solid, has no clearly defined melting point. However, at temperatures below the glass transition temperature, glass is most definitely solid. Actually, metals exhibit more "liquid" behavior than glass does, because they will creep under load, something glass does not do.
2006-11-13 17:06:34 · answer #1 · answered by injanier 7 · 0⤊ 0⤋
Urban legend.
See the link below and start reading from "Glass as a liquid."
Summary: At room temperatures, it doesn't flow, and the fact that the window is thicker at the bottom than at the top is an artifact of the way the window was manufactured and installed.
2006-11-13 20:15:48 · answer #2 · answered by Anonymous · 1⤊ 0⤋
Teacher fell for it, sorry. Glass doesn't flow like a very viscous liquid.
Medieval glaziers were clever and put the thicker glass at the bottom as it makes the window more stable.
2006-11-15 16:40:37 · answer #3 · answered by black sheep 2 · 0⤊ 0⤋
Yes your teacher is right. If you go into a really old house or church and look at the windows (or stained glass), you will find the bottom of the glass to be thicker than the top. Mind you this doesn't happen in a year or even 10 years - this takes many many many years.
2006-11-13 19:53:41 · answer #4 · answered by KJ 5 · 1⤊ 1⤋
My understanding is that this is true.
I have never tested it myself, but remember this being taught when I was studying engineering in college.
Apparently, if you find a window that has been installed for several years, you can measure the thickness and find that the bottom of the window will be thicker than the top of the window becuase of this very slow flow.
2006-11-13 19:55:48 · answer #5 · answered by an engineer 2 · 1⤊ 1⤋