Have you ever noticed that a drop of cream sometimes appears to hover on the surface of coffee? Well, MIT researchers have some answers. Via VOX:
Scientists at MIT recently solved the mystery of why this happens in a study published Wednesday in the Journal of Fluid Mechanics. Turns out it has to do with the temperature difference between the hot coffee and the cold cream.
MIT scientists explain that when the drop of cream first hits the surface of the coffee, a bit of air becomes trapped between the drop and the rest of the liquid. That air acts as a buffer, and it has to be pushed out before the drop can continue to merge with the surface.
If the cream and coffee are the same temperature, they’ll merge within a few milliseconds. But if there’s a big temperature difference, tiny vortexes of air form along the gradient, keeping the trapped air in place.
When the MIT scientists performed the experiment, they used silicone oil, which, depending on preparation, can mimic the properties of water as well as more viscous liquids. In these experiments, the scientists were able to make a drop of the oil float on the surface of a basin of silicone oil for as long as 10 seconds if the temperature difference was 86 degrees Fahrenheit.
Anyone who has admired the swirling patterns cream makes in coffee can appreciate this finding. But it could actually help advance medicine too: Researchers say the insight — and the mathematical models they built to predict how long the drops hover — could aid in engineering new “labs on chips,” where tiny droplets of chemicals could run diagnostic medical tests or mimic reactions in body cells.
Adafruit has had paid day off for voting for our team for years, if you need help getting that going for your organization, let us know – we can share how and why we did this as well as the good results. Here are some resources for voting by mail, voting in person, and some NY resources for our NY based teams as well. If there are additional resources to add, please let us know – adafruit.com/vote
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.