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Volta’s Hailstorm and Electrophorus

This inexpensive electrophorus set works great! 
From Amazon: BUY NOW Electrophorus Demonstration Set 

The container is just the middle part cut from a plastic water bottle, and the "hail" stones are Styrofoam craft beads: 
From Amazon: BUY NOW Styrofoam Craft Beads 

For Volta's Hailstorm to work, the beads must be coated with a conducting spray (here is what I used): 
From Amazon: BUY NOW Staticide Spray 

Wikipedia has a very nice description of the physics of the Electrophorus and how it is used to transfer electric charge. 

Volta’s Hailstorm and Electrophorus: electrical forces due to electrostatic charge send foam beads flying in this version of the historic demonstration by physicist Alessandro Volta. The beads are covered with an electrically conductive coating allowing them to transfer charge from the environment to the plate of the electrophorus. The acrylic platform becomes negatively charged when rubbed with a paper napkin, but it is also an insulator so the charge on it can not flow on to the aluminum plate of the electrophorus. Instead the charge on the platform pushes electrons to the top of the plate (like signs repel) and touching the plate results in a spark that removes the electrons giving the plate a significant positive charge that will then attract the beads. 

Scrap Metal Kinetic Sculpture

The nested curves revealed with this device are related to the Lissajous curves. 
Learn more on Wikipedia: Lissajous curve 

Click this links for a readily available kinetic art system that produces similar curves.

Scrap Metal Kinetic Sculpture: a bent spring becomes a coupled harmonic oscillator with two modes of oscillation, one along a horizontal direction and one at an angle. As the kinetic energy trades back and forth between these two modes the end of the spring traces out a Lissajous curve (revealed by a white LED) which gets smaller in size each cycle as friction dissipates energy from the system. The full beauty of this motion is captured by recording the light traced using the Slow Shutter Cam App which unveils the nested family of curves.($1.99 in App Store, Cogitap Software)


High Tech Rain Stick

Available here: 
From Amazon: BUY NOW 
Acrylic Rain Stick 

From eBay: BUY NOW 
Acrylic Rain Stick 

Get the spectrum analysis app here: SpectrumView - Oxford Wave Research Ltd.

Wikipedia has nice articles about white noise and other colors of noise described with the math of spectrum analysis 

High Tech Rain Stick: white noise- the sound of two thousand metal spheres falling and bouncing through a plastic labyrinth creates a power spectrum of sound waves with all frequencies at equal intensity, creating the shhh sound we often encounter from many random processes. Part of the cascade slowed to 240 FPS midway through video.

Coins of Constant Width

These triangle coins are often available on eBay.

Fron eBay: Search NOW: Bermuda Triangle Coin

The silver proof versions can be expansive, but sometimes the circulated coins (like those in the video) are available at a lower price.

Click to see more: shapes of constant width

Coins of Constant Width: the only coins produced in the shape of the Reuleaux triangle, issued in 1997 and 1998 by Bermuda. The special convex shape of the Reuleaux triangle will roll, because like a circle they have the same diameter from one side to the other, no matter their orientation. To demonstrate this property note here how two straightedge rulers remain parallel as the coins rotate between them, just as one would expect circles to behave! Bermuda triangle (ha!) coins were only produced for two years and featured Elizabeth II on the front and shipwrecks on the back- this one depicts the wreck of the Sea Venture.

Ultimate Solid of Constant Width

Available in three metals and two finishes.
From The Matter Collection: 
Order NOW: Ultimate Solid of Constant Width- Brass
Order NOW: Ultimate Solid of Constant Width- Steel
Order NOW: Ultimate Solid of Constant Width- Copper

Ultimate Solid of Constant Width: Reuleaux tetrahedrons with specially calculated curved edges become volumes of constant width- possibly the minimum volume that can possess this property. The shape featured here is a new discovery of a solid of constant width that has perfect tetrahedral symmetry. Made from solid steel, brass, and copper- these shapes have constant diameter no matter their orientation and will roll like spheres between two planes- note how the acrylic plate remains parallel to the desktop as the orbiforms roll in between. Currently available on Kickstarter from my friends at the Matter Collection : Reuleaux tetrahedrons with specially calculated curved edges become volumes of constant width- possibly the minimum volume that can possess this property. The shape featured here is a new discovery of a solid of constant width that has perfect tetrahedral symmetry. Made from solid steel, brass, and copper- these shapes have constant diameter no matter their orientation and will roll like spheres between two planes- note how the acrylic plate remains parallel to the desktop as the orbiforms roll in between. Currently available from my friends at the Matter Collection 


Pendulum Clock

Affordable gravity powered pendulum clocks available here in a number of styles:

From Amazon: BUY NOW: Pendulum Clock

The version featured in the video is the: Hermle Ravensburg Clock

Gravity Powered Pendulum Clock: invented in 1656 by Christian Huygens, the physics properties of a swinging pendulum was the basis of all precision clocks until the 1940s. As noted by Galileo, the period of swing of a pendulum can be made very precise and stable depending only on its length. This modern version is made faithfully in the original design powered only by gravity as the potential energy of the descending weight is transferred to the kinetic energy of the drive train gears and pendulum. The key feature of any pendulum clock is the anchor escapement mechanism- a curved piece attached to the pendulum with two prongs that only allows the escapement wheel to move forward one tooth per swing cycle, and producing the characteristic “tick-tock” sound. The weight descends about 1 cm per hour, and when hanging from a wall the chain needs to be pulled once a week, raising the weight up about 2 m to keep the clock in operation. This beautiful clock, made by Hermle, features a chime that sounds upon the hour. 

Oscilating Cylinder Steam Engine

Get this tiny working engine here: (brass and stainless steel) 

From engineDIY: BUY NOW: Tiny Steam Engine

Two other similar mini-engines to consider: BUY NOW: Mini-Steam 1, Mini-Steam 2 

Oscillating Cylinder Steam Engine: a functional “wobbler” type piston steam engine complete with boiler and flywheel. In this design the cylinder and piston both rock back and forth, acting as the valve mechanism to allow the hot steam to enter through a small hole, and then exit on the next stroke out through the tiny exhaust port in the top. Takes about 4 minutes to get going after the lamp is lit. A tiny version of the invention that powered the industrial revolution.

Mirror Vision Puzzle

More than three versions of this puzzle out there. Get one here:

From Amazon: BUY NOW: MIrror Vision Puzzle

From eBay: BUY NOW: Mirror Vision Puzzle

Mirror Vision Puzzle: this Harry Potter themed puzzle has only 9 pieces but each supplies two parts of the final image- without the mirror one gets only half the picture. The top of each square is a corrugated lenticular composition of two images, and when viewed from the correct angle only one image can be seen directly, with the other reflected in the mirror, which combine in this case to reveal the famous phoenix bird of the HP stories. Flipping over the puzzle squares produces a second image to solve, this time a basilisk. An ingenious puzzle form from inventor/designer Mark Setteducati and sold by Mattel.


Poly acrylamide Polymer Vanishing Act

Get some of these grow-spheres here: 
From Educational Innovations: BUY NOW Growing Spheres 

Poly-acrylamide Polymer Vanishing Act: these spheres of hydrophilic polymer have an almost identical index of refraction as that of water- thus when submersed they become invisible. Note the elasticity of these spheres from the way they bounce, while at the same time they refract their surroundings as a spherical lens. The super absorbent spheres start as hard crystals with a radius of 2mm and grow to 11mm when immersed in water. So much physics going on here! 

In-Feed Google 2

Beat Interference Chimes

Get a set here: 
From Educational Innovations: BUY NOW Beat Interference Chimes 

Wikipedia: Features a nice introduction and helpful graphics explaining the physics of this beat interference phenomena

Beat Interference Chimes: these aluminum chimes resonate at slightly different frequencies. When both chimes are struck the sound waves interfere both constructively and deconstructively producing the interesting wavering sound called a beat. The beat frequency- the rate at which the sound goes loud to quiet- is equal to the difference between the frequencies of the two chimes. The same physics applies when tuning a guitar using fifth and seventh fret harmonics.


Impossible Dovetail

Inexpensive versions of this "impossible box" like that in the video avaiable here:

From Amazon: BUY NOW: Impossible Box Puzzle

Impossible Dovetail: this impossible object is pretty common, but it is a classic, and included in my collection. If one assumes a regular dovetail joint then this construction would indeed seem impossible without cutting and gluing, but what one sees from the sides makes for misleading assumptions as this box opens easily. Swipe for reveal once you’ve thought about about possible constructions. 

Trammel of Archimedes

Get similar devices here: 

From Etsy: BUY NOW 
Trammel of Archimedes

From eBay: BUY NOW 
Trammel of Archimedes

Trammel of Archimedes: as the shuttles take turns completing their straight line journeys, the end of the crank arm traces an ellipse. Sometimes sold as a “do nothing machine” or “nothing grinder”, far from doing nothing this simple and crucially important mechanism demonstrates how rotational motion can be converted into translational oscillatory motion- such as how a piston can drive an engine’s crankshaft. This version was crafted from fine maple, cherry, and oak by artisan Neal Olsen. 

Impossible Bottle Sculpture Puzzle

Mr. Evans makes a variety of amazing impossible bottle sculptures: 
From impossiblebottle.co.uk: Buy NOW Impossible Bottles by Philip Evans 

Nice Impossible bottles are often available on Etsy: 
From Etsy: BUY NOW Impossible Bottles

Impossible Bottle Sculpture Puzzle: seemingly impossible, but created with clever engineering, this “impossible” bottle contains a padlock and full deck of cards still in the wrapper (a cut out in the side of the box reveals that all the cards are inside). The puzzle aspect is to consider how the bottle was produced (I personally have some theories- but I do not know the secrets of this artist). I can tell you with high certainty that the bottle was never cut or altered in anyway, and it was not somehow formed around the objects. This bottle by Phil Evans is one of the best I’ve seen. 


Magnetic Chaotic Pendulum

Available here: 
From eBay: BUY NOW 
Magnetic Chaotic Pendulum 

Magnetic Chaotic Pendulum: adding magnetic forces to gravity gives this pendulum chaotic motion- not random, but very sensitive to slight differences in initial launch conditions. Arranging the dipoles magnets on the base leads to different patterns of motion- here the center magnet attracts and the rest are set to repel. ROMP pendulum by Hog Wild toy company. 

Dudeney's Dissection

Get this version here: 
From Grand Illusions Ltd: Dudeney's Dissection 

A nice wood version is available here: 
From Etsy: BUY NOW Dudeney's Dissection 

See both Wikipedia and Wolfram MathWorld for more details on the history and math of this geometrical oddity. 

Dudeney's Dissection: an equilateral triangle can be cut (dissected) into four pieces that will then assemble into a square. Interestingly the four parts are all different in shape (the green and yellow pieces are similar but not the same). This hinged model is comprised of precision machined and anodized aluminum, and can be folded back and forth between the two simplest regular polygons. It is not known if a similar three piece dissection is possible. Also called the haberdasher's problem and described in 1907 by Henry Dudeney it is the only 4 piece solution known.

Tornado Spheres

Get a set here: 
From Amazon: BUY NOW Tornado Spheres

Get a concave mirror like the one in the video for less than $3 here: 
From Amazon: BUY NOW Concave Mirror  

And get a set of inexpensive colored lights here: 
From eBay: BUY NOW Color LED lights 

Tornado Spheres: two ball bearings welded together can be made to spin up to 2000+ rpm by the Magnus Effect using a stream of air. Shining three colored LEDs on the spinning pair produces an illusion of floating rings along with a second illusion that these rings are rotating and changing direction due to aliasing with the frame rate of the video camera (like the famous wagon-wheel effect).