Cork in Bucket: Brain Teaser from Braingle

Question:
A cork, say from a wine bottle, is held by a robotic clamp at the bottom of a bucket of water and released the moment the bucket is dropped off the side of a tall building. What will happen to the cork during the fall? Will it float to the top of the bucket normally, slower than normal, faster than normal, or not at all? Assume that there is no air resistance to slow the bucket down.

HEY! DON'T JUST LOOK AT THE ANSWER! THINK ABOUT IT!

Answer:
The cork will stay at the bottom of the bucket and not float up at all during the fall, since the cork, the bucket and the water all fall at the same acceleration g (neglecting air resistance as all good physics questions do). The buoyant force of the water does not push the cork upward in this case since in free fall the buoyant force is zero. In other words, a cork only floats up when the water around it is heavier and pushes it up. In free fall the water is weightless, as is the cork and bucket, so there is no force to push the cork to the top of the bucket.

Snippets:
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ARIN WHOIS Database Search by the American Registry for Internet Numbers: Find out who an IP address belongs to.
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Video: Amelie (2001). w/ Audrey Tautou. In French with English subtitles. Introverted Paris girl spices up other people's boring life. Worth seeing!
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The 'Cavendish Experiment' can be used to determine the gravitational constant of the earth (G) using an apparatus (torsion balance) designed by geologist John Mitchell (1724-1793). It was first used and improved by Henry Cavendish (1731-1810) who, in 1798, used the results to calculate the average density of the earth. This allowed calculation of earth's mass ("weighing the earth") and G.

Other Links:
- The Mitchell-Cavendish Experiment by Laurent Hodges, Iowa State University.
- Measuring the Mass of the Earth by Donald G. York, Univ. Chicago; contains experimental setup and calculations. (requires Adobe Acrobat)

Cork in Glass: Brain Teaser from Braingle:

Question:
If a cork is put into a glass of water, the cork will almost always drift to the side of the glass. There is one simple way, however, to get the cork to float on the surface in the center of the glass. What is it? Water, the glass, and the cork are all that is required.

HEY! DON'T JUST LOOK AT THE ANSWER! THINK ABOUT IT!

Answer:
The reason that a cork drifts to the side of a glass is that it floats to the highest point. Since water "clings" to the glass, the highest point is around the edge of the water. To get the cork to float in the middle of the glass, all you have to do is fill the glass as much as possible. The water will form a convex shape above the glass, with the highest point at its center. This is where the cork will settle.


Snippets:
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Richard Feynman: Six Easy Pieces (Audio of physics lectures given in 1961/1962): When you take an apple and magnify it to the size of the earth, then the atoms in the apple are about the size of an apple.
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Notes to Book: Curt Suplee: Physics in the 20th Century (1999)

Laser = light amplification by stimulated emission of radiation
Precursor: Maser = microwave amplication by stimulated emission of radiation

Microwaves have longer wavelengths and therfore less energy than visible light

Einstein: Atoms can emit photons in two different ways: spontaneous (e.g., sun, light bulbs) and stimulated (maser, laser).

When an atom is excited by a quantum energy that exactly corresponds to one of its specific allowed energy states (postulated by Niels Bohr), it absorbs the energy, but then almost immediately sheds it by emitting a photon. Variation of effect: If an electron is already in an excited state and then struck be a photon of excactly the right energy, it emits two photons. The new photon is identical to the first; each quantum of radiation is perfectly matched, meaning the new photon is exacty in phase with the one that stimulated its emission: 'coherent'.

Snippets:
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Video: "Cassatt" (Portrait of an Artist Volume 2: May Cassatt. Impressionist from Philadelphia. Produced by WNET/Thirteen for 'Women in Art' (1977), 30 min. Cassatt was, after Whistler, the most important American Impressionist Painter; she spent much time painting in Paris; she was a close friend of Degas; they thoroughly critiqued each others work; especially known for her mother-child portraits.
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Video: Big. w/ Tom Hanks. A 13-year old boy makes a wish at a fair and slips into the body of a grown-up. Funny; childish at times; Hanks plays the role real well.
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Brain-Teaser: The Flash Mind Reader. Can you find out how it works?
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Design: Ritzenhoff (in German). Lots of pictures.
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Designer: Michal Shalev, b. 1958 in Tel-Aviv, Israel; carpet and textile designs, also curtains, paper products, porcelain and shower curtains; has been working closely with such German firms as Ritzenhoff, Karstadt, Rosenthal, Design House since 1994.
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Metric System Prefixes: Exta = 10^18, Peta = 10^15, Tera = 10^12, Giga = 10^9, Mega = 10^6, Kilo = 10^3
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Dynamic Planet Blog
TOC: Table of Contents
July 2003

1.) Herman Hesse: Siddhartha
2.) Geometric Brain Teaser
3.) Mortimer J. Adler: Aristotle for Everybody
4.) Brain Teaser: Coffee with Cream