Skipping a stone on water requires a flat, disk-like stone thrown at a shallow angle, but elastic spheres are remarkable skippers, too, even at higher impact angles. Researchers at the Splash Lab have just published their work on why these balls skip so well. As seen in the top animation, the elastic spheres deform on impact, flattening to a more disk-like shape that rides at an angle of attack relative to the air-water interface. Both features are important to the spheres’ enhanced skipping. By flattening, the sphere comes into greater contact with the water and by orienting at a larger angle of attack, the sphere increases the vertical component of force the water generates on the sphere. It’s this vertical force that lifts the sphere up and lets it keep bouncing.  

Because the ball is soft, it keeps deforming after its impact and bounce (see top animation). For some skips, the timescale of the sphere’s elastic waves is smaller than the length of time the sphere is in contact with the water. When this is the case, the sphere’s elastic waves will affect the impact cavity in the water, forming what the researchers call a matryoshka cavity, after the Russian nesting dolls. An example is shown in the second animation. For more, check out the USU press releasethe original paper, or the award-winning video they made a few years ago.  (Image credits: J. Belden et al./The Splash Lab)

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Elastic spheres can walk on water. Incited by public fascination and engineering application, water-skipping of rigid stones and spheres has received considerable study. While these objects can be coaxed to ricochet, elastic spheres demonstrate superior water-skipping ability, but little is known about the effect of large material compliance on water impact physics. Here we show that upon water impact, very compliant spheres naturally assume a disk-like geometry and dynamic orientation that are favourable for water-skipping. Experiments and numerical modelling reveal that the initial spherical shape evolves as elastic waves propagate through the material. We find that the skipping dynamics are governed by the wave propagation speed and by the ratio of material shear modulus to hydrodynamic pressure. With these insights, we explain why softer spheres skip more easily than stiffer ones. Our results advance understanding of fluid-elastic body interaction during water impact, which could benefit inflatable craft modelling and, more playfully, design of elastic aquatic toys.”


Little Robot – A girl with a messenger bag full of tools finds a misplaced robot

Little Robot
by Ben Hatke
First Second
2015, 144 pages, 7.3 x 9.2 x 0.6 inches
$12 Buy a copy on Amazon

I am a sucker for little girls that can hold their own. The nameless little girl in Ben Hatke’s latest book does just that. She is independent, resourceful, and not afraid to go it alone. This graphic novel for the younger set tells the story of an isolated little girl who finds a misplaced robot and the friendship that ensues. She teaches him about the world from the beautiful (“Its a flower, its alive too.”) to the simple joy in skipping stones. The story darkens slightly as the company who misplaced our robot sends out a pretty ominous creature of its own to track and retrieve the little guy. It’s a touch of Johnny Five and a bit of WALL-E. When the little robot wants to stretch his wings is where the story gets interesting. While this little girl makes a friend, she isn’t always a good one. The little robot enjoys her company, but longs to connect with others more like him. While they are navigating their friendship, they must face the machine that continues to hunt them down.

Little Robot bridges the gap between picture book and graphic novel with its detailed illustrations and sparse dialogue (however it features lots of great sounds - making it all the more fun to read aloud). It’s enjoyable for children regardless of reading level as toddlers can page through the emotive illustrations and older children can take their time with the plot.

Little Robot is timely in that it fits perfectly within the current STEM and Maker movement. The little girl carries a messenger bag of tools that are her lifeline throughout the story. Also, there are the robots - adorable robots. Little Robot is a great introduction to comics and my current go-to present for the children in my life in hopes of exposing them to something slightly off the shelf. – Amy Lackpour

February 5, 2016

I find comfort
in others holding
their own pain.
Me holding mine.

Like little gray rocks;
flat and smooth,
cold on our
warm summer palms.
Fingertips whisper across its edges.

I am here.
Standing at the edge of the creek,
skipping stone in my hand.
I know with the flick of a wrist,
I could let it go.

Watch it graze and tremble the water.
Watch how much the rippled waves change the surface
before sinking
to the bottom of its belly.

And finally,
everything else will seem so still again.
Only a memory of the descent.
Only a rock stationed at the bottom.

Silent memorial for submersion.
Silent prayer in remembrance
of all the waves.

It’s Valentine’s Day and once again they are celebrating at a fancy local restaurant. As is tradition this place employs a live jazz band but the once intimate harmony of instruments has become a somber collection of guilty beats who mesh together, although beautifully, now out of obligation.

The meals have filled them to content but a portion remains on their plates. You can see it has been constantly picked at, and if they were to taste it they would feel the once sizzling plates have gone cold, only being heated now by the lone flickering candle light between them. He looks up at her, she at he. An exchange of brief smiles as their gaze shifts past each other to the other couples in vibrant lighting and lovely conversations. 

The thought enters: Have we become the dining the dead? What am I missing?

Over the past year or so, Gallant has gone onto prove why he’s one of the most exciting singers around. Having released a number of stellar releases in the lead up to 2016, the crooner is set to set the scene aflame with his debut album which is now finished and should be dropping later this year. Before that though, we’re treated to “Skipping Stones”, a stunning duet between Gallant and Jhene Aiko. Together, Gallant’s effortless falsetto and Aiko’s soft, graceful musings are a match made in heaven as they rise over the grand instrumental laid down by Adrian Younge and Stint. Just in time for Valentines Day, as part of the Red Bull Sound Select, listen to the track above…

Poetic Ideal: a language scrubbed clean by silences.

If we listen, the air is heavy with poems, ripe for plucking.

Branches are roots, too, in the sky.

Perhaps it is not poetry that purifies the language of the tribe, but Silence.

The true poet, or mystic, is not too proud to admit that, in matters great and small, they cannot proceed until they receive further instructions.

One never becomes a poet, except when they are writing a poem.

Yahia Lababidi, Skipping Stones,” Berfrois (12 October 2012)