Get the kit here:
From Educational Innovations: BUY NOW Polydensity Bottle Kit
Folow the link above for details of the physics explanation.
Poly Density Puzzle: my favorite science brain teaser- white beads and blue beads "float" oddly separated beneath the surface of a clear liquid. If the contents are mixed by shaking the container, the white beads gather at the top and the blue sink to bottom! Adding to the mystery; after about 30 seconds the two layers of beads will have slowly moved back to the middle. What is your guess as to the physics behind this behavior?
Get one here:
From Edicational Innovations: BUY NOW: Switch Pitch Ball
Switch Pitch Ball: this spherical assembly changes color by turning inside out when tossed into the air. A favorite of my mechanical toys with surprising physics. Interestingly the advertisements for this toy incorrectly claim air drag is involved in the transformation. To understand why the ball inverts first note that the ball is made of multiple components hinged together. In launching the ball from the hand an upward acceleration results in a torque that pivots each component around its center of mass, causing the rotation of these components in an organized way leading to the transformation. Imagine tossing a stick straight up. If the stick is perfectly vertical upon launch it will move straight up- but if it is initially slanted at all it will also begin to rotate upon launch. Similar physics underlies the motion of each component of the ball- shown here in 240 fps slow motion. The Switch Pitch is produced by the makers of the Hoberman Sphere.
Get the kit here!
From Educational Innovations: BUY NOW Melting Snowman Kit
Viscoelastic "Melting Snowman": non-newtonian flow is demonstrated by these blobs of viscoelastic silicon polymer (aka Silly Putty) in the shape of snowman- if force is applied over a short period of time the substance shows elastic properties (bounces like a superball), but if the force is applied slowly the substance flows like a viscous liquid (flattens under gravity over a few hours as shown here). Thus this snowman does not melt because it is already liquid, one that flows slowly though. Mostly sold as a toy, Silly Putty was discovered after mixing boric acid with silicone oil during World War II in an attempt to find a rubber substitute.
Here is an affordable version of this device:
From Educational Innovations: BUY NOW Flow Ring
The original version is available here:
From Amazon: BUY NOW Toroflux
Get one and flow with it!
From Art of Play: BUY NOW
Why does it look like a bubble when moving fast? Wikipedia has the details: when the object exceeds a certain speed the flicker fusion frequency of our vision produces the bubble illusion.
The physics of the toroflux is wonderfully illustrated and explained in this article by Daniel Walsh.
Toroflux: kinetic art toy made from a single continuous loop of stainless steel band. The band of spring metal is woven such that it forms a torus that can clamp on to and roll down a stick, segment of tubing, or even an arm. Amazing combination of math and kinetic art invented by Jochen Valett.
Get one here!
From Educational Innovations: BUY NOW PhiTOP
From Amazon: BUY NOW PhiTOP
The PhiTOP: spinning things often have surprising physics! This unique top is made of solid aluminum in the shape of a prolate elIipsoid- and the name of the top is derived from the following design requirement: the ratio of the semi minor (short) axis to the semi major (long) axis is made equal to the mathematical constant the golden ratio φ (phi). Invented by astrophysicist Kenneth Brecher, this top stands up vertically (when spun with sufficient rotational velocity) due to physics similar to that of the tippy-top.
Liquid crystal sheets, thermochromic fun!:
From Educational Innovations: BUY NOW liquid crystal thermometer sheet
Thermochromic Chiral Liquid Crystals: the thin layer changes color as the molecules of the liquid crystal change orientation and spacing during the phase transition from liquid (warm) to crystal (cool).
Many colors (and two sizes) to choose from:
From Educational Innovations: BUY NOW
From Amazon: BUY NOW
The physics of the liquid rope-coil effect is pretty complex. Here is a recent scientific paper on the topic with nice illustrations.
Journal of Fluid Mechanics: Multiple coexisting states of liquid rope coiling
Ooze Tube: viscous polyisobutene fluid timer toy. Some interesting physics phenomena are found in this kinetic art novelty item: the "liquid rope-coil effect" where the fluid thread coils and stacks as it lands on the pooling surface, and a curious periodicity in the rate of flow that is related to the formation of non-spherical bubbles as the air and fluid trade places (shown in time-lapse). The physics of the coiling effect is complex (see the link in my blog). Broadly speaking the coiling is due to the bottom of the fluid rope widening at the contact point with the surface, and as it widens the fluid slows down but not evenly. This uneven rate of flow produces a bend and the elasticity of the stream constrains the rope to a limited radius- hence a stack of coils.
Get one here:
From Educational Innovations: BUY NOW Magnetic Sand Timer
Magnetic Sandglass: 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 as they attempt to align with the magnetic field lines. These stacks topple over due to gravity creating interesting patterns.
Available in "pro" metal version and colored rings version:
From Educational Innovations: BUY NOW Jitter Gyro Ring
From eBay: BUY NOW Color Jitter Gyro Ring
Jitter Gyro Ring: a 1990s skill toy craze out of New Zealand that features small rings that "roll" down a thicker steel ring and making a characteristic chattering sound as they go. Swiping the small rings gets them spinning and gives them angular momentum. Centripetal acceleration then keeps the inside of the small rings in contact with the steel ring so that they roll around as they descend (seen here in 240fps slow motion). The challenge is to rotate the large ring fast enough to keep the small rings in motion.
This particular sculpture is no longer available, however, Educational Innovations has this nice and affordable starter kit:
From Educational Innovations: BUY NOW Diamagnetic Levitation Kit
Dramatic diamagnetic levitation kits are available here: the racetrack magnets are a bit pricey though!
From eBay: BUY NOW Diamagnetic Levitation Kit
Diamagnetic Trap Sculpture: a thin disk of pyrolytic graphite hovers and spins in stable equilibrium over a bullseye configuration of magnetic poles. Diamagnetic substances become temporary magnets while immersed in an external magnetic field, and the created diamagnetic field always opposes the external field (in contrast to ferromagnetic substances like iron which attract). Graphite of this type is one of the strongest diamagnets known, and will levitate over a powerful array of neodymium magnets. ✨With sincere appreciation to Tim Rowett for this kind gift.
Get some magnetic viewing film here:
From Educational Innovations: BUY NOW Magnetic Viewing Film
From Amazon: BUY NOW Magnetic Viewing Film
Magnetic Poles of Refrigerator Magnets: visualizing the invisible with Magnaview film- the secrets of refrigerator magnets revealed. A special orientation of the magnetic poles called a Halbach array allows for a strong magnetic field on one side and a very weak one on the other- refrigerator magnets only stick on one side by design!
Plasma globes are now available in many sizes and levels of quality. Here is a source for reasonably priced quality globes:
From Educational Innovations: BUY NOW Plasma Globe
From Amazon: BUY NOW Plasma Globes
Plasma Globe: low pressure noble gasses exhibit glow discharge from high voltage, creating plasma filaments that rise upward due to heating- shown here in slow motion. A small high frequency coil at center creates the high voltage potential between the center electrode and the metal coated glass globe. Current flow through the thin gas produces the colorful emission spectra from the gasses
The essence of a great physics toy: simple design showing comlex physics
From Educational Innovations: BUY NOW Reaction Rocket
Reaction Rocket: projectile launch via momentum transfer in slow motion. The superball/straw base bounces off the table top and then immediately collides with the bottom of the rocket sending it off with a velocity slightly less than 3 times the velocity of the rising ball (true if the ball is more than three times the mass of the rocket). Newton's third law in action! Note that the rocket rises much higher than the drop height (up to 9 times higher).
Get one here! Chose your color scheme and length, all come with the special motor and operating instructions:
From Educational Innovations: BUY NOW: Dancing Helix
The Dancing Helix: This kinetic mobile's mesmerizing motion arises from pulsed torsion waves that propagate up and down the length of a series of weighed rods connected by an elastic ribbon (which acts as a torsion spring). The waves arise by a special pulsed motor from which the strand hangs, and only spins for a second or so out of each minute. The twisting waves then constructively and deconstructively interfere creating an array of flowing motions.
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.
Three Polarizing Sheets: quantum mechanical behavior with light polarization. Two linear polarizing sheets oriented at 90 degrees blocks all light- if a third sheet is placed between, oriented at 45 degrees, an eighth of the original light then gets through! A classic example of the quantum mechanical phenomenon of superposition of states as it pertains to the polarization orientation of photons and probability of transmission.
Get a sample from these sources:
From Ebay: BUY NOW Nitinol Memory Wire shape sample
From Educational Innovations: BUY NOW Nitinol Memory Wire Spring
Nitinol Memory Wire: this alloy of nickel and titanium can be trained to a specific shape at high temperature- then bend it up at room temperature and it will snap back into shape when exposed to moderate heat such as hot tea water. This remarkable property is a type of solid state reversible phase transition known as a martensitic transformation.