Zito,+Allison

Motion Detectors

It was extremely surprising to learn that there are a variety of motion detectors, considering that the only one I am familiar with is the infrared light beam. Similarly, although I had always known about the way bats use echoes to collect their food, I didn’t really realize that their technique was incorporated into our lifestyles – like automatic doors. However, the most surprising of all was that motion detectors measure warmth. I did know that snakes used warmth to detect their pray, but I had no idea that measuring heat was used for motion detectors like some people put outside their homes. I also found that this pertained to Central, where a lot of classrooms and all of the bathrooms are motion detecting. They probably use the echo or warmth system. Finally, it was interesting to know that the amount of energy in particles of light was determined by frequency, rather than intensity.

Allison, Very good! You were very thorough! I think you are right about the detectors around here. btw it's "prey" not "pray". 5 stars! MW

Could Cell Phone Radiation Damage Our Brains?

Reading the title of the article, I became extremely concerned because of the dependence on cell phones within our society. However, after reading, I learned that damage from cell phones isn’t actually possible. In fact, another common item like the microwave emits more radiation than do cell phones. The radiation by cell phones only heats up the skin by a fraction of a degree, and is millions of times less than something like an x-ray. In order to create damage to the brain, a cell phone would have to be continuously pressed against someone’s head. Ultimately, cell phones are safe to use and shouldn’t be of any concern to us.

Allison, Well done! I agree. Let's not worry about the cell phone. There are plenty of other things that are much more harmful. 5 stars. MW

Redefining The Kilogram

In the article, “Redefining The Kilogram,” I was extremely surprised to learn that the standards of measurement are so important throughout the world, and that the official kilogram is kept in a vault. It’s strange to thing that a unit of measurement needs so much protection, and I was especially confused by how the official standard in Paris had lost 50 ug over time compared to its copies. Additionally, I was surprised to learn that only 90 copies of the official kilogram in France exist throughout the world today. With 7 billion people on the planet, and so many people studying science and chemistry, there must be many more copies. I thought it was really interesting that all measurement standards are defined by a physical property of nature, while the kilogram isn’t. Overall, I didn’t realize how much attention is given to the kilogram, but the current global standard seems to be doing well.

Allison, The kilogram's loss of mass is a major concern in some circles. We probably wouldn't really notice it but it's probably best to redefine in as a constant term. 5 stars. MW