In the video above, sound waves passing around and through a drop of mercury set it oscillating. But the physics of the system — determined by things like the speed of sound in mercury and the strength of its surface tension — allow some sound waves to excite special vibrations in the drop. In other words, the mercury drop has resonances with the sound at specific frequencies.
These are called the resonant modes of the drop. When the frequency of the sound waves matches the frequency of the drop’s resonant modes, highly organized patterns of pulsation are triggered. You know you’ve hit strong resonances when something like a multiple-armed, star-shaped pattern emerges.
It’s a remarkable reminder of the hidden architectures embedded in the world around us.
Watch as pen spinners Ian Jenson and 吳宗諺 (PPM) perform some epic pen spinning, complete with a few great slow motion moments that really showcase what’s going on. This short from Taiwan’s Kuma Films makes us want to get some weighted spinning pens, but anyone can start practicing with an everyday pencil, too: How to Spin a Pencil Around Your Thumb.
When light travels through areas of different air density, it bends. You’ve probably noticed the way distant pavement seems to shimmer on a hot day, or the way stars appear to twinkle. You’re seeing light that has been distorted as it passes through varying air densities, which are in turn created by varying temperatures and pressures.
Schlieren Flow Visualization can be used to visually capture these changes in density: the rising heat from a candle, the turbulence around an airplane wing, the plume of a sneeze … even sound.
BionicKangaroo is able to realistically emulate the jumping behavior of real kangaroos, which means that it can efficiently recover energy from one jump to help it make another jump. Without this capability, kangaroos (real ones) would get very very tired very very quickly, but by using their tendons like elastic springs, the animals can bound at high speeds efficiently for substantial periods of time.
BionicKangaroo emulates this with an actual elastic spring, which partially “charges” the legs on landing.
Bonus fun: wear the corresponding armband and you can control the kangaroo using gestures. Mmmmmmm, biomechanics.
That moment that ketchup transitions from a solid, high up in the ketchup bottle, to a liquid that squirts all over your fries – that moment is a big physics moment. Why? Ketchup is a non-Newtonian fluid(like oobleck, peanut butter, custard, toothpaste, paint, blood, or quicksand) that can switch between a solid and liquid state, and ketchup is non-Newtonian in two different ways…
In that transition moment, ketchup may be responding to a strong, quick force, suddenly making it thinner, or if you’re patient and apply just a wee bit of force, it may start flowing given some time and gravity. Grab a ketchup bottle and get the details in this TED Ed lesson by George Zaidan, with animation by TOGETHER.