Buettner,+Devon

I read an article about coins called the captivating chemistry of coins. Metallic money has been around for thousands of years and paper money has only been around for a couple hundred years. The metal is worth less then the coin to prevent people from melting it. All coins today are made from alloys. These are a mixture of two or more elements and one has to be metal. Alloys are harder and more durable. Gold and silver are soft and can't endure the circulation. People started using bronze (mixture of copper and tin) to make them. Now they use a bronze alloy of 95% copper, 4% tin, and 1% zinc.

Devon, Looks like you picked out some interesting things! I like your descriptions of various metals and alloys. 5 stars! MW

Redefining The Kilogram:

One interesting thing that we kind of learned is that the Kilogram is one of the seven base units of the International System of Units. Also, The kilogram is the last of the SI base units that is still defined by a physical artifact rather than by an unvarying physical property of nature. The last interesting thing is, something we also learned in class. Its that the prototype is kept in a vault. It also has 6 copies at the International Bureau of Weights and Measures near Paris.

Devon, OK. Pretty basic but 5 stars. MW

Motion Detectors:

In the article Motion Detectors, one interesting thing I learned is that the term hertz is named after Heinrich Hertz who was named after the unit for light frequency. I also thought it was interesting about the 3 techniques for motion detectors. I didn't know that there was a light source, another sends out pulses and the last uses warmth. I just thought when you go by it notices movement. Last, I learned that particles of light are called photons and that the intensity only went off the amount of photons. 90

Devon, OK. Looks good! 5 stars. MW