Budget physics

Dudeney's Dissection 3D Print

Get this set here!

From Etsy: BUY NOW: Dudeney's Dissection 3D Print

Dudeney's Dissection: an equilateral triangle canbe cut (dissected) into four pieces that will then assemble into a square. This 3D printed version comes as a puzzle- fit the pieces in each of two containers- a square and a triangle, which also makes it clear the two supplied shapes are of equal area. Fun fact: It is not known if a similar three piece dissection is possible. Also called Haberdasher's problem and described in 1907 by Henry Dudeney it is the only 4 piece solution known.

Impossible Braid 

Get this nice example of mystery braid here:

From Art of Play: BUY NOW: Impossible Braid Key Fob

Here is a great video on how to make the mystery braid

See other Impossible Objects in my collection. 

Mystery Braid: challenge- how can three strands be braided if both sets of ends are connected? (swipe for reveal) A new addition to my collection of “impossible objects”, this leather key fob is braided from a single piece of leather, constructed by making two parallel slits but not cutting the ends. The solution is well known to those in the field of leatherwork- due to a twist of topology it’s possible to make this braid if the number of left strand over right crossings equals the times the right strand crosses over the left. Four strands braided this way is not mathematically possible, but 3, 5, or any odd number can be done!

 

 


Static Spheres

Get this inexpensive device here:

From Educational Innovations: BUY NOW: Static Spheres

Click here for other static electricity devices

Static Spheres: triboelectric effect toy. The red acetate spheres are given an acquired net negative charge, and their mutual repulsion allows them to jump a centimeter or more as charge is manipulated on the PET plastic container. Bringing an object near the container momentarily moves electrons (charge) around creating repulsive forces (sphere v. sphere) and attractive forces (spheres and container) resulting in the observed motions. The red spheres interact with each other without coming into physical contact (as shown in 240 fps slow motion) as like charges repel. Shaking the system a bit allows the red spheres to pick up charge in the first place by colliding with the container.


In-Feed Google

LASER Pointers + Diffraction Grating

Need a laser pointer? Incredibly, you can get 3 (one of each color) for under $20 (including S&H): 
From Amazon: BUY NOW Red+Green+Purple Laser Pointer

Rainbow Symphony has a nice selection of diffraction gratings and sun catchers:
From Amazon: BUY NOW: Diffraction Grating Toys

LASER Pointers + Diffraction Grating: three frequencies of laser pointer- Red (635 nm), Green (532 nm), and Blue (450 nm). Note that the distance between the intensity maxima (bright spots) is greatest for the red (long wavelength) and closest for blue (shortest wavelength) with the green in between. The diffraction grating is the same form as one of those rainbow fireworks glasses- this one from has 13500 lines per inch. 

Balance Pteranodon

Get one here! 
From Amazon: BUY NOW Balance Pteranodon 
From eBay: BUY NOW Balancing Pteranodon

Balance Pteranodon: weights in the forward wing tips create a center of mass below this pterosaur's beak- making a system that can rotate and oscillate about a stable equilibrium condition. No magnets used or needed for this physics! Usually this toy is found in the form of a bird (direct dinosaur descendent). Pterosaurs are not dinosaurs, but are the largest animals to ever fly, and powered flight has only evolved four times: bats, birds, pterosaurs, and insects- in reverse order. 


Electric Motor/Generator

Amazingly this motor is available for less than $10 US. 

From Amazon: BUY NOW: Brushless Motor/Generator with LED

Electric Motor/Generator: this inexpensive and common motor can also serve as a generator of AC electricity- here lightning an LED when the shaft of the rotor is spun by hand. Most electrical energy we use today is produced by moving a magnet near a coil of wire (known as Faraday’s law of induction) to produce an electric current. Removing the permanent magnet casing reveals this design to use 9 separate copper windings. I made a transparent second rotor with six neodymium magnets- and when these magnets are made to move near the windings the LED again lights with the flow of current. Swipe to see the beautiful magnetic field pattern of the rotor design using magneview film.

TrueBalance

Get the full version (8 disks made of wood) or the mini (6 disks, blue or red plastic): 
From Amazon: BUY NOW TrueBalance Coordination Puzzle 

TrueBalance: coordination challenge puzzle- get the six disks, connected by bearing swivels, into a vertical stack by only tilting the handle. Harder than it looks to get each disk’s center of mass above the one below at the same time into the unstable equilibrium final state. The swivels constrain the system, limiting the degrees of freedom, and allowing strange and interesting motion. Kinetic art as a toy! 


Magnetic Sand Hourglass

Get one from these fine sources: 
From Amazon: BUY NOW Magnetic Hourglass 

Magnetic Sand Hourglass: ferromagnetic sand collects above a neodymium magnet in the wood base. Each particulate of ferromagnetic iron becomes a temporary dipole magnet in the presence of the magnetic field in the base. The tiny dipoles link up north ends to south ends, creating interesting patterns that reveal the magnetic field lines. 

Polarization Test Card

These inexpensive test cards are available here: 
From eBay: BUY NOW Polarization Test Cards

Get some polarizing filter sheets here: 
From Amazon: BUY NOW Polarizing Sheets 

Explore many aspects of polarization with this kit: 
From Educational Innovations: BUY NOW Polarizing Filter Demo Kit 

See this short introduction to linear polarizing filters on Hyperphysics, and many more details on polarization from Wikipedia

Polarization Test Card: light has features that are invisible to the human eye, such as the orientation of its electric field (denoted as polarization), but can be revealed to us by a polarizing filter, used to block light with specific polarization orientations. Inexpensive test cards like this are often found in shops selling polarized sunglasses. The molecular structure of plastics can rotate the polarization of any light that passes through, and this card has such thin layers added to the top of the photo to create the hidden silhouettes seen here. 

 

Strandbeest Mini

Get one here! Make sure to get the Jr. Scientist version of this kit for best results. 
From Amazon: BUY NOW Strandbeest Model Kit 

Read about Theo Jansen and his novel leg linkage mechanism for the Strandbeests via these Wiki pages. 

Strandbeest Mini: A fully working model of artist Theo Jansen's Strandbeest kinetic sculpture which features Jansen's linkage- a unique leg mechanism which converts rotary motion of a crackshaft into smooth walking motion. Jansen's creations are usually a couple meters high and walk the beaches of the Netherlands powered by the wind. This version comes as a model kit that snaps together with no glue- a really fun project!


Tensegrity for the Desk

Get similar tensegrity sculptures here:

From Etsy: BUY NOW: Tensegrity Sculpture

Tensegrity for the Desk: an elegant, and stackable, desk toy version of this popular tensegrity configuration by maker/designer Micah Murdoch. Constructed from poplar wood, the design assembles easily with clever ball and socket connectors at the ends of the nylon support lines (3 long, 1 short). Stacking them seems to only increase the illusion of floating with the subtle way these structures defy gravity. Another fun configuration of tensegrity concept, invented by Kenneth Snelson and made famous by the architect Buckminster Fuller in 1949.

Mini Waving Tube Guy

Get this inexpensive and silly toy here:

From Amazon: BUY NOW: Wacky Waving Inflatable Tube Guy

This power supply reccomended: BUY NOW: 9V power supply

Mini Waving Tube Guy: the physics of fluid dynamics describes the flopping behavior of the famous dancing tube guy. Bernoulli’s principle tells us that when air is moving with a velocity, the pressure in the region of the moving airmass is reduced. When the tube guy stands strait, air escapes through his head and arms allowing a temporary steady velocity of flow which reduces pressure inside and he collapses and bends. When the tube is bent, airflow is cut off, and the tube inflates like a balloon building pressure until air can again escape through the top- and the process cycles back and forth between these two states creating the iconic dance moves. This desktop version uses a 9V battery to power the fan.

Mini-Drinking Bird Heat Engine

Small and large drinking birds available here:

From Amazon: BUY NOW: Mini-Drinking Bird Heat Engine

See more drinking birds in my collection

Mini-Drinking Bird Heat Engine: this hummingbird sized heat engine is the latest species added to my drinking bird collection. This little guy comes with the traditional top hat and his own plastic goblet- which is the perfect height for a standard drinking bird to share. Cooling by evaporation at the head leads to lower pressure in the top bulb, the pressure in the bottom bulb pushes the dichloromethane fluid up the neck making the bird top heavy and the bird tips over dipping its beak and letting the fluid return to the bottom bulb. The process repeats, and as long as the top stays wet and cooler than the bottom this heat engine will continue to cycle.