- show the movie on scale
- review from last week:
- about investigations: example: on sphere packing
- surface tension, capillary forces, and jellies
- lab demonstration: melting ice cubes
- lecture on cold and warm materials
- next week: sticky greasy dry and powdery
Why do some materials feel cool to the touch, even at room temperature? Why do others feel warm? Why do others feel neutral? Today we will look at some examples, melt some ice, try to pass a ball through a ring, and offer some ideas about how to talk about temperature and materials.
- Christopher Hall. “Materials: A Very Short Introduction” Hot and Cold
- Miodownik, Mark. “Stuff Matters : Exploring the Marvelous Materials That Shape Our Man-made World.” CH5: Marvelous Foam.
- Aerogel
“The continuity of the liquid permeating jellies is demonstrated by diffusion, syneresis, and ultra-filtration, and the fact that the liquid may be replaced by other liquids of very diverse character indicates clearly that the gel structure may be independent of the liquid in which it is bathed.” What he is saying in this opening paragraph is that various experiments have shown that the liquid in a jelly is connected throughout, rather than being compartmentalized, and can be replaced by other liquids.
questions
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what does jelly have in common with setting cement?
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what are capillary forces? and how do capillary forces related to surface tension?
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why do things expand when heated?
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what is heat?
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surface tension (surfActants)
- thermal expansion
- specific heat
- thermal conductivity
Willem ’s Gravesande built his ring-and-ball apparatus in Leiden in ~1740.
An iron ball made so that it will just pass through a ring will not pass after it has been heated.
Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change.