Density has been in the news since… well, since Archimedes shouted Eureka. We have collected a sampling of news stories about density that you may want to use in your classroom as you open a discussion about this fascinating subject.
If you find a news article about density that you’d like to share, please let us know in the comments section. Happy reading!
News from the Past
Do your students know the story of Archimedes and the king’s crown? Here it is, courtesy of VisionLearning:
Sometime around 250 BCE, the Greek mathematician Archimedes was given the task of determining whether a craftsman had defrauded the King of Syracuse by replacing some of the gold in the King’s crown with silver. Archimedes thought about the problem while relaxing in a bathing pool. As he entered the pool, he noticed that water spilled over the sides of the pool. Archimedes had a moment of epiphany. He realized that the amount of water that spilled was equal in volume to the space that his body occupied. This fact suddenly provided him with a method for differentiating a mixed silver and gold crown from a pure gold crown. Because a measure of silver occupies more space than an equivalent measure of gold, Archimedes placed the craftsman’s crown and a pure gold crown of equivalent mass in two tubs of water. He found that more water spilled over the sides of the tub when the craftsman’s crown was submerged. It turned out that the craftsman had been defrauding the King! Legend has it that Archimedes was so excited about his discovery that he ran naked through the streets of Sicily shouting “Eureka! Eureka!” (the Greek word for “I have found it!”).
The Truth about Quicksand and Density
Despite all the movies that show unfortunate adventurers being submerged to their necks (and more) in quicksand, we’re relieved to learn that human beings do not automatically sink in quicksand. The reason? You guessed it: density. This National Geographic News article explains the details.
Is the Arctic Ocean Getting Spicier?
Image source: ScienceNews.org
Did you know that seawater is characterized as being either “spicy” or “minty,” depending upon its relative salinity and temperature? Warmer, saltier ocean water is considered spicy while cooler, fresher water is deemed to be minty.
The Arctic Ocean is getting spicier, according to an April 2016 report in the Journal of Physical Oceanography. As the region warms due to climate change, temperature will have an increased influence on Arctic seawater density. The result, according to Yale University oceanographer Mary-Louise Timmermans, is somber: “The way the Arctic Ocean works will change.”
The World’s Lowest Density Ice?
Illustration: Yingying Huang and Chongqin Zhu
Researchers in Nebraska have reportedly created a new molecular form of ice that would be the world’s lowest density ice. If their ice can be synthesized, it would become the 18th known crystalline form of water—and the first to be discovered in the United States since before World War II.
As Xiao Cheng Zeng, an Ameritas University Professor of chemistry who co-authored the study, explains, “Water and ice are forever interesting because they have such relevance to human beings and life. If you think about it, the low density of natural ice protects the water below it; if it were denser, water would freeze from the bottom up, and no living species could survive. So Mother Nature’s combination is just so perfect.”
If confirmed, the new form of ice will be called “Ice XVII.” An illustration of the ice’s molecular configuration is shown at right. To learn more about this discovery, read the article here.