DIY

The Orb Drop IV

A new KickStarter campaign from engineer and maker extraordinaire Rian Suiter. Rian has delivered on each all 11 (eleven!) of his creative physics toy related KickStarter campaigns to date. Check out his latest here: 
From KickStarter: Order NOW Orb Drop IV marble run track 

The Orb Drop IV: @orbdrop has created another fun DIY marble run- this one uses an Archimedean screw mechanism to bring the marbles continuously back to the top where they are launched along one of three paths- including a vortex funnel. Gravitational potential energy is transformed to the kinetic energy of the orbs as they loop and negotiate the banked turns of the snaking tracks. Three AA batteries and a small motor power the transport assembly. 

Hyperbolic Holes

This inexpensive kit available here:

From Amazon: BUY NOW: Hyperbolic Holes Kit

Hyperbolic Holes: a straight rod, in this case a pencil, glides through a symmetrical pair of curved holes. The design is based on the hyperboloid, the 3D ruled surface traced by an offset rotating diagonal line. This device is sold as an inexpensive kit to assemble yourself, and includes a motor with geared drive and pre-cut pieces. The pencil is my addition- sharpened to just the right size to clear the curved openings.

Homopolar Motor

Fairly simple to make- here are the inexpensive supplies needed to make a few of these motors. 
AA batteries have a diameter of 14.5 mm, so a bottom magnet with a diameter of 15 mm is just right: 
From eBay: BUY NOW Neodymium Disk Magnet 

Wire that looks and works well is just 10 gauge ground wire. Inexpensive and available at any local hardware store-- or order a small quantity here: 
From eBay: BUY NOW 10 gauge Copper Wire 

Wikipedia has some good details on the physics of homopolar motors 

Homopolar Motor: a minimalist electric motor- battery, wire, and magnet. This type of motor does not need a commutator- the polarity of the electromagnetic coil does not need to reverse. The challenge with this design is balancing the coil to center on the battery as it rotates. A favorite DIY physics toy!


Self Propelled Homopolar Motor

Here are disk magnets I used for the "wheels": 
From eBay: BUY NOW Neodymium Disk Magnets 
From eBay: BUY NOW Neodymium Disk Magnet 

Wire that looks and works well is just 10 gauge ground wire. Inexpensive and available at any local hardware store-- or order a small quantity here: 
From eBay: BUY NOW 10 gauge Copper Wire 

Wikipedia has some good details on the physics of homopolar motors 

Self Propelled Homopolar Motor: cylindrical neodymium magnets supply the static magnetic field for this motor and become the wheels of a very simple vehicle with an AA battery as the energy source. As soon as both ends of the copper wire make contact, an electric current will flow which in turn induces a magnetic field around the wire. This induced field around the copper wire will then interact with the neodymium magnets on each end causing them to spin- a wonderful example of a motor with minimal components.

The FluoroSphere

The kit includes the UV LED base, elegant glass sphere, and enough fluorescent gel for many repeat lights shows. 

From PyroFarms: BUY NOW: FluoroSphere

From Amazon: BUY NOW: FluoroSphere

The FluoroSphere: intricate and dynamic lights shows are produced within an elegant glass sphere as fluorescent dyes in mineral oil slowly mix into room temperature water. Ultraviolet LEDs (in the base on which the sphere rests) make the dyes glow brightly and reveal the initial nondiffusive mixing structure which includes the phenomena of drops, plumes, and other features of Rayleigh-Taylor instabilities. Shown here, slightly sped up, is the first 8 minutes or so of the process which takes up to half an hour to mix evenly. The green light is characteristic of the famous fluorescein dye.

 

Floating Yen

Aluminium 1 Yen coins are the perfect denisty to float as shown in the video:

From Etsy: BUY NOW: 1-Yen Coins

Floating Yen: the surface tension of water is strong enough to suspend the aluminum coin, and a trapped column of air in a second glass can submerge a portion of the surface with the coin. The 1-Yen coin has just the right mass and density for this demonstration. One of my favorite DIY physics demonstrations.


Polarizing Filter Black Wall Illusion

Amazon lists acrylic tubing at a reasonable price: get a 2 foot long tube with an inner diameter of 1.5 inches for about $17 US. This will accommodate a large marble for the demonstration. 
From Amazon: BUY NOW Acrylic Tubing 

For a 1.5 inch inner diameter (3.8 cm) tube you will need a 10 inch (25.4 cm) wide sheet to complete a cylinder inside the tube. 
From Educational Innovations: BUY NOW Polarizing Film

Polarizing Filter Black Wall Illusion: two sheets of polarizing film (with polarization axes oriented at 90 degrees to each other) create this illusion inside an acrylic tube. Physics magic!

Frabjous Geometric Sculpture Puzzle

Get one here- five colors to choose from:

From MoMath: BUY NOW: Frabjous Sculpture Puzzle

Frabjous Geometric Sculpture Puzzle: 30 identical laser cut acrylic pieces interlock into 12 interconnected five point stars (each with a spiral vortex center) in this puzzle based of the Frabjous sculpture by artist and professor of mathematics George Hart (Prof. Hart is now on Instagram, follow him at @george.hart.sculptor to see more of his amazing work.) Note that if one connects the tips of the stars one gets the outline of a dodecahedron, with its 30 edges and 12 sides, and if one considers the face planes of the linked pentagrams the underlying shape is a polyhedron called the “great rhombic triacontahedron”. A year or so ago I got to visit the National Museum of Mathematics in NYC where I bought this puzzle in the @momath1 museum shop. This puzzle was great fun to assemble- buy one to support this inspirational museum, and make a great sculpture for your bookshelf! 

"Impossible" Domino

Get the 3D print files here:

From Cults3D.com: Download Now: Impossible Domino

This video from The Action Lab has a good decription of rhe physics. 

“Impossible” Domino: a pair of specially engineered domino type objects where the right domino knocks over the left one, but then stands back up! When seen in slow motion the process becomes more clear. The main factor here is that the center of mass of the left domino is higher than that of the right one, giving it much more potential energy so when the left one topples over it can transfer some energy back to the right one. Created by the folks at viralvideolab and 3D printed by my friend Roger Key (thanks!)


Harbottle Air Pressure Demonstration 

This item came to me in my Spring 2022 Curiosity Box subsciption:
Get (or give!) a Curiosity Box subscription here: JOIN NOW: The Curiosity Box

A nice glass version is available from this trusted seller:
From Educational Innovations: BUY NOW Harbottle Demonstration 

Harbottle Balloon Demo: a regular untied balloon remains inflated- one can even look down the neck of the balloon and see inside! Just blow up the balloon inside the bottle and then cork the hole in the opposite end- in so doing the inside of the balloon is experiencing the full force of air pressure, but the exterior of the balloon is protected from the crush of air pressure by the rigid wall of the bottle. Air pressure at sea level is 10.1 Newtons of force per each square centimeter of area (14.6 pounds per square inch). The bottle allows a pressure differential, pressure on the inside but much less on the outside of the balloon. The inside air pressure would lead to 12.5 pounds of force pushing outward on a 2 inch diameter balloon- more that enough to balance the elasticity of the rubber balloon material. Take the cork out and now both sides experience the same air pressure and the elastic force is no longer balanced. A fun demonstration reminding us that we live at the bottom of a deep sea of atmosphere! 

Salt Fractionation

All the ingredients are available from your local market/drugstore. The trick is to find a dye that works for acetone, but will not color water- believe it on not blue glitter will color the acetone nicely and not change the salt water. Follow this link for details: 
ChemEd X: Blog of Prof. Tom Kuntzleman 

Of course Amazon has what you will need:

From Amazon: BUY NOW 
acetoneblue glitterfood coloring, cool bottle 

Salt Fractionation: two liquids that won’t stay mixed! Acetone (dyed blue) floats on top of the higher density salt water (dyed orange). Acetone usually dissolves in water through hydrogen bonding interactions, but solubility can be altered. In a process called “salting out” a sufficient amount of salt is dissolved such that the water molecules, which are much more attracted to the resulting Na+ and Cl- ions (through ion-dipole bonds), will then ignore the weaker acetone hydrogen bonds. This results in the spontaneous separation (shown here in real time) of the liquids no matter how well shaken up. 

Compliant Mechanical Elephant

Get the .stl files for this 3D print here:
From Thingiverse: Download NOW: CM Elephant

Learn more: mechanical engineering of compliant mechanisms

Compliant Mechanical Elephant: a demonstration of engineering using flexible elements instead of pivot joints when creating linkages. In this whimsical and clever linkage design a sideways translation of the elephant creates only rotation at the tip of the pachyderm’s trunk. Note that the hole at the end of the trunk remains eerily stationary as the body translates horizontally back and forth. This demonstration model comes from the Compliant Mechanisms Research group at Brigham Young University. Thanks once again to Roger Key for producing this 3D print. 


Ferromagnetic Interaction

Here is the NdFeB neodymium magnet used in this video:

From Amazon: BUY NOW: Neodymium Disk Magnet

Please use extreme caution when handeling strong magnets like this one. Small nails, paperclips, staples and other houlshold object made with iron will interact interestingly with the magnetic feild. 

Ferromagnetic Interaction: iron rich nails temporarily become dipole magnets in the presence of an intense magnetic field from a large neodymium super magnet. Here the neodymium disk magnet is set with its north pole pointing up, so the point of each nail becomes a south pole (repelling each other) and the head of each a north pole. Imbued with these temporary induced fields, the nails will try to align themselves with the neodymium dipole’s field like compass needles, and the nails will interact with each other in interesting ways.

Repelling Marbles Puzzle

Get this affordable and fun kit here:

From Educational Innovations: BUY NOW Mystery Marbles Puzzle Kit 

Mystery Marbles Puzzle: a physics brain teaser (now available as a kit) what's going on here? Three glass marbles can move but stay separated in this liquid filled tube no matter the orientation- why do they not touch? Swipe for reveal of components. 

See also: Poly-acrylamide Polymer Vanishing Act


Magnetic Suspsension Sculpture

This DIY magneits sculpture can be assemebled with these parts.  Bring a magnet into a craft shop to find some necklace chain that is non-magnetic. 
From Amazon/eBay: BUY NOW: Quilting HoopNeodyumium Sphere Magnets

Magnetic Flux Gyroscope art and other amazing science inspired jewelry available here:
From Foxtail Jewelry: BUY NOW: Kinetic Magnetic Pendants
From Foxtail Jewelry: BUY NOW: Tabletop Magnetic Kinetic Art

Magnetic Suspension Sculpture: two neodymium magnets on chains suspended by their mutual magnetic attraction in this prototype kinetic sculpture (swipe to see scaled fine jewelry version by foxtailjewelry). These powerful magnets hold the chains taut with about a 2cm gap. Made from a quilting hoop where the magnets connect under their own force to steel nails soldered on to non-magnetic chain.

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.

Reflection and Refraction of a Cyan Laser Pointer

Get this beautiful new color of laser pointer here: 
From eBay: BUY NOW: 488nm Laser Pointer (Cyan)

Blocks of polished acrylic available here:
From eBay: BUY NOW: clear acrylic block

Reflection and Refraction of a Cyan Laser Pointer: a new affordable wavelength laser pointer that just came on the market- 488nm producing a beautiful hue of blue. The beam is made brightly visible as internal reflection constrains most of the laser light to propagate along the interior of this block of acrylic (similar to the physics of fiber optics).