The Reynolds number R is the dimensionless combination:
in which ρ is the density, ν the speed of the fluid, R the size of the flow, and η the viscosity. When R ≤ 1, friction dominates inertia and the fluid flows in layers (laminar flow).Here we are using corn syrup which has a viscosity of 5 (Pa s); its viscosity is 5000 times that of water, and the Reynolds number R is less than unity.This experiment is being demonstrated by Kevin Cahill for his Biophysics II students.The couette cell used in this experiment was fabricated by John DeMoss in the Machine Shop of the Department of Physics and Astronomy at the University of New Mexico.
Teachable Moment: This brilliant little video made by the Royal Observatory in Greenwich covers the concepts of parallax, doppler and red-shift and shows how they are all used together to measure the universe.
Teachable Moment: This is a great synthesis of how a series of clearly important, yet seemingly disparate, equations have been used together to provide us modern conveniences.
Without equations, most of our technology would never have been invented. Of course, important inventions such as fire and the wheel came about without any mathematical knowledge. Yet without equations we would be stuck in a medieval world.
Teachable Moment: Beautiful perspective of the stars as seen from the Space Station.
Timelapse videos depicting the stars from low earth orbit, as viewed from the International Space Station. Images edited using Adobe Lightroom with some cropping to make the stars the focal point of each shot, and with manipulation of the contrast to bring out the stars a bit more.
From year to year, the moon never seems to change. Craters and other formations appear to be permanent now, but the moon didn't always look like this. Thanks to NASA's Lunar Reconnaissance Orbiter, we now have a better look at some of the moon's history. Learn more in this video!
Teachable Moment: I have always been a sucker for good visualization but this visualization of 120,000 numbers plotted in a dynamic and interactive narrative opens the mind to the possibilities in visualization.
Hans Rosling's famous lectures combine enormous quantities of public data with a sport's commentator's style to reveal the story of the world's past, present and future development. Now he explores stats in a way he has never done before - using augmented reality animation. In this spectacular section of 'The Joy of Stats' he tells the story of the world in 200 countries over 200 years using 120,000 numbers - in just four minutes. Plotting life expectancy against income for every country since 1810, Hans shows how the world we live in is radically different from the world most of us imagine.
Teachable Moment: Who wouldn't want to have a tangible periodic table... the fact that Theo Gray made an actual table out of it is a bit quirky but an engaging way of doing it!
Some people collect stamps. Wolfram Research co-founder and author Theo Gray collects elements. Step into his office, and you'll see a silicon disc engraved with Homer Simpson, a jar of mercury, uranium shells and thousands of other chemical artifacts. But his real DIY masterpiece is the world's first "periodic table table." Within this masterfully constructed table-top lay samples of nearly every element known to man, minus the super-radioactive ones.
Teachable Moment: Circles have so many fun properties and are a great way of introducing basic geometric shapes.
"Geometry of Circles" is a series of unnumbered animation pieces created for Sesame Street in 1979. Cathryn Aison commissioned Philip Glass to write music for animation based on her storyboard which had been submitted to and approved by Edith Zornow of CTW.