Chemistry

Hot water freezes faster than cold - and now we know why. Hot water seems to freeze faster than cold water, known as the Mpemba effect. The effect was named after the Tanzanian student who in 1963 noticed that hot ice cream mix freezes faster than a cold one. The effect was first observed by Aristotle in the 4th century BC, then later Francis Bacon and René Descartes. Mpemba published a paper on his findings in 1969. Theories for the Mpemba effect have included: faster evaporation of hot water, therefore reducing the volume left to freeze; formation of a frost layer on cold water, insulating it; and different concentrations of solutes such as carbon dioxide, which is driven off when the water is heated.

Simulador Ondas Agua Loading... Made by Evan Wallace This demo requires a decent graphics card and up-to-date drivers. Consciousness: More like Fame thanTelevision February 26, 1995 Consciousness: More like Fame than Television Daniel C. DennettCenter for Cognitive StudiesTufts UniversityMedford, MA 02155 All Nobel Prizes in Chemistry The Nobel Prize in Chemistry 2002 "for the development of methods for identification and structure analyses of biological macromolecules" John B. Fenn and Koichi Tanaka "for their development of soft desorption ionisation methods for mass spectrometric analyses of biological macromolecules" Simple Physics Demos This past weekend, the Louisiana Section of the AAPT participated in the joint NSTA-AAPT Physics day. The most popular presentation was the “really simple and cheap physics demos”. Lots of participants asked about the demo details. Although I posted a simple list of the demos, I figured it wouldn’t hurt to give slightly more detail. So, here you go.A note about the demos.

Make Your Own Co2 Fire Extinguiser Materials: - Candle- Wire Coat Hanger- Two 1 liter plastic soda bottles- Matches- Baking soda- Vinegar- Pliers and Scissors- Adult Supervision Watch the Co2 Fire Extinguisher Video Process For Making Your Own Co2 Fire Extinguisher 1) Use the scissors to cut off the tops of the plastic bottles. Iron Man - The Real Iron Man Suit For the Stan Winston Studio IRON MAN team, the biggest challenge was to create suits that retained their well-known comic book proportions while still allowing Robert Downey Jr. and his stuntmen to perform with minimal discomfort and maximum range of motion. Shane Mahan, 25 year SWS FX supervisor and co-founder of Legacy Effects said, “For Robert to be in the Mark III suit was a culmination of a great many steps because we had to take a design that is non-human in some of its proportions and fit actors and stuntmen into it.” To add to the complexity of the job, Mahan added, "We were forced to reverse-engineer the suit because we didn’t have Robert’s body cast to build the suit over joint-for-joint, measurement-for-measurement. The digital build and design of the suit was 95 percent complete before Robert was even cast in the film."

Interactive Lecture Demonstrations in Economics The Interactive Lecture Demonstration is designed to help students learning core concepts in economics using a classroom activity that may be an experiment, a survey, a simulation or an analysis of secondary data. The activity creates a motivation for students to learn economic analysis presented in a follow-up lecture. The Interactive Lecture Demonstration differs from most classroom activities such as economic experiments in that it follows a framework in which students: Predict an outcome Experience the demonstration Reflect on what they learned Why use Interactive Lecture Demonstrations? Interactive Lecture Demonstrations are an effective way to help students learn fundamental economic concepts because: In economics, many concepts are counter-intuitive or defined in a manner different from their colloquial usage. For example, most people misperceive the effect of economic growth (Christandi and Fetchenhauer 2009).