Recent Posts

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. 

Popsicle Stick Bomb

Craft sticke work great:

From Amazon: BUY NOW: Stick Bomb Supplies

Amazingly: There is a Wikipedia entry on Stick Bombs and their physics

Popsicle Stick Bomb: a form of simple tensegrity, the elastic potential energy of the bent sticks is dramatically released under application of a slight concussive force such as an impact with a table top- shown here in forward and backward slow motion (swipe to see three more explosions). Shown here is one of the simplest constructions with 5 flat sticks woven into a spring-loaded configuration held in place by friction and tension induced by the bending of the wood. A nice demonstration of energy conversion- potential to kinetic.

Reverse Cartesian Diver

Glass divers available here: 
From Amazon: BUY NOW Glass Divers 

The reverse diver needs a bottle with a oval shaped cross section. I used the bottle from this product- it has the right shape and size and the label comes off easily: 
 
From Amazon: BUY NOW Oval Shaped Bottle Source 

Inexpensive and fun diver kits available here: 
From Educational Innovations: BUY NOW Cartesian Diver Kits 

Wikipedia has the details on the Cartesian diver (and reverse diver)

Reverse Cartesian Diver: physics puzzle (swipe for hint). On the left is a Cartesian diver- pressing on the bottle forces water into the glass diver, which then compresses the bubble in diver’s head allowing it to sink. On the right is a reverse Cartesian diver- again the bottle is pinched but this time the diver ascends- why? 


Mirror Anamorphic Cup & Saucer

Get a set here: 
From Etsy: BUY NOW 
Anamophic Cup & Saucer 

Mirror Anamorphic Cup & Saucer: the cylindrical mirror of the silver cup reflects and reveals the distorted scene of a carousel ride with four horses and the buildings of Macau Heritage City. The shape of the mirror allows for a mathematical operation, a type of affine transformation, to map the distorted image on the plate to the restored image reflected on the cup. A nice example of mirror anamorphosis through the medium of ceramics. 

Wringing Guage Blocks

Guage block sets can be a bit pricy, but some fairly inexpensive pieces and small sets can be found for demonstrations and such:

From Amazon: BUY NOW: Gauge Blocks

Wikipedia has a nice description of Gauge Blocks and the Phenomenon of Wringing

Wringing Gauge Blocks: two blocks of metal (not magnets!) will stick together by a process called wringing if their surfaces are flat to high precision- such as these gauge blocks found in most machine shops. Here two blocks are forced apart with a snap, and then wrung back together with the characteristic sliding motion technique. Gauge blocks are flat to less that one millionth of a meter and are used by machinists for precision length measurements and calibration. The science of the wring force remains somewhat a mystery and no one has yet found a fully excepted physics description- but we do know that blocks will wring in a vacuum and that the force can be up to 30 times that of weight of the blocks. Fun physics from the shop!

Van de Graaff Generator

This device is sold as the "Static Shocker" hands on lab. Get one here for $8.95! : 
From Educational Innovations: BUY NOW Static Shocker Mini Van de Graaff 

The device can use an empty aluminum can for the top electrode which works- but this $9 hollow steel sphere looks and works even better- I used the 80mm sphere: 
From eBay: BUY NOW Hollow Steel Sphere 

Van de Graaff Generator: this miniature electrostatic generator can create potentials of more than 50,000 volts allowing sparks to jump a couple centimeters through dry air. Similar physics to the sparks created when shoes scuff on carpet, a moving rubber dielectric belt carries electrons away from the top sphere leaving it positive charged- as can be seen by the electrostatic repulsion of some Mylar strands. A small battery powered 3V motor drives the belt via the bottom pulley in this unit that costs less than $10 US.?With appreciation to @educational_innovations for sending me this device! 


How a Slinky Falls

Get the classic here: 
From Amazon: BUY NOW Mini Slinky 

Get a giant version of the slinky here! 
From Educational Innovations: BUY NOW Giant Slinky: Super Wave Spring 

How a Slinky Falls: amazing physics demonstration with this classic toy. The center of mass of the slinky spring falls with an acceleration of g- note in this slow motion video that the bottom of the slinky does not move until the spring is fully collapsed. Hooke's law plus gravity! 

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.

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! 

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. 


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).

The Levitron

Levitron Tops were produced in the 1990s and are out of production and getting harder to find. Some models are still available here: 
From eBay: BUY NOW 
Levitron Top 

The Levitron: spin stabilized magnetic levitation- will fly for about 3 minutes or more per launch. The spin rate of the magnetic top must be just right for flight, not too fast or too slow. Air resistance and dissipative interactions between the magnets gradually slow the spin rate and the top falls. Interestingly trapping the top requires precision - the weight of the top must be adjusted to within 1 gram to achieve equilibrium between the pull of gravity and the magnetic repulsion from the large donut shaped magnet in the wood base. Repost of my favorite physics toy in my collection.

Corona Discharge Trajectories

Mini Tesla coil with wire end attachment: 
From Amazon: BUY NOW 
Mini Tesla Coil 


Long exposure image captured using this Slow Shutter app: 
 
From App Store: BUY NOW 
 Slow Shutter Cam 

Click this link for more information and uses of this mini Tesla Coil 

Corona Discharge Trajectories: the ejected electron stream propels the end of a thin wire connected to a miniature Tesla coil. The corona discharge creates a glowing plasma at the end of the wire, but also imparts momenta that pushes the wire’s end into a final state circular orbit. The more interesting behavior occurs during the initial transient orbits which seem to be hypotrochoid type curves beautifully captured here using the Slow Shutter app. Please see seven posts back for details about this mini Tesla coil. 


Kostick Stars

Two versions available here: 
From Art of Play: BUY NOW 
Kostick's Stars 


Here is the detail of the connections of the 6 star from the patent document: 
 
Learn more about John Kostick here: John and Jane Kostick handcrafted mathematical constructions

Kostick Stars: The geometric forms of these kinetic sculptures snap into place due only to the balanced tension forces between thear slightly bent bronze wires. The large star is comprised of six struts, each made of 5 wires, which are made to intersect and weave though each other with beautiful geometric regularity. Similarly the small star has 4 struts each made of 3 wires. The ends of the 6 struts of the large star become the 12 vertices of an icosahedron, and the ends of the 4 struts of the small star point to the 8 corners of a cube. Both stars can be collapsed along many of the symmetry axes. Invented and patented in 1970, these stars are still produced and sold by artist and designer John Kostick. 

Ambiguous Superhero Object 

Available now- 3D printed ambiguous object Illusion:

From Amazon: BUY NOW: Superhero Ambiguous Object Illusion

From eBay: BUY NOW: Superhero Ambiguous Object Illusion

More of this type hereAmbiguous Object Illusions on @physicsfun 

Ambiguous Superhero Object: A very fun fan art 3D print which makes use of the ambiguous object illusion invented by mathematician Kokichi Sugihara- a clever combination of reflection, perspective, and viewing angle. Printed and sold by 3DNY Design. 

Gifeez: Modern Phenakistiscope

This amazing toy for under $10: 

From Amazon: BUY NOW: Gifeez Animation Toy

Gifeez: a modern zoetrope type device with built in strobe light to explore the physics and psychophysics of motion animation- still images flashed in rapid succession produces the illusion of motion through persistence of vision. This inexpensive device has two modes: 1) the strobe frequency is set to various ratios of the spin frequency creating fascinating motion of abstract geometrical images, and 2) the strobe is set to animate simple cartoons. When the image flash rate is above the flicker fusion frequency (approximately 16Hz) we perceive fluid motion- the basis for all movies and TV. This device includes a centripetal switch that turns on the strobe and a motor that keeps the disk spinning for a couple minutes and comes with 15 printed double sided disks and a few blanks to allow for your own designs.