Educational Innovations

Poly Density Puzzle

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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?

The PhoTOP

Get a PhoTOP from these fine vendors (comes with laser pointer!):

From Educational Innovations: BUY NOW PhoTOP 
From Vat19: BUY NOW: PhoTOP

Another amazing spinning device by Prof. Ken Brecher! Get his other spinning tops here:
From Etsy: BUY NOW: PhiTOP, PiTOP, eTOP, iTOP, DeltaCELT

The PhoTOP: phosphorescent glow illuminates the intricate path of a 405nm laser pointer beam on a balanced spinning disk. Let the disk set alone for a few minutes to allow the traces to fade- and repeat again and again to experiment making new patterns.

The Dancing Helix

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.


Viscoelastic Melting Snowman

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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.

Electric Motor

Get this easy to assemble kit here: 
From Educational Innovations: BUY NOW Simplest Motor Kit 

Electric Motor: in its simplest form!- coil, magnet, and battery. The wire of the coil has an insulating coating- and this coating is carefully scrapped off one side on each end. When current passes through the coil it becomes an electromagnet and the permanent magnet repels it making it spin- as it turns the currents goes on and off depending if the copper posts are in contact with the bare wire (current on) or the still insulated wire (current off). I have motors with fewer parts- but they operate on more complex principles.

Ooze Tube

Many colors (and two sizes) to choose from: 
From Educational Innovations: BUY NOW 
Ooze Tube 

From Amazon: BUY NOW 
Ooze Tube 


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.


Toroflux

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 
The Toroflux


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.

The PhiTOP

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. 

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.


Switch Pitch Ball

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. 

Magnetic Sandglass

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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.


In-Feed Google

Magnetic Poles of Refrigerator Magnets

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!

Nitinol Memory Wire

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. 
 


Exothermic Crystallization Heat Pack

Available in many sizes and colors: 
From Educational Innovations: BUY NOW Click Activated Resuable Heat Pack 
From Amazon: BUY NOW Click Activated Reusable Heat Pack 

Exothermic Crystallization Heat Pack: real-time instant crystallization of a supercooled solution. Solid sodium acetate melts at 137F (58C), but it will stay in liquid form as it cools to room temperature creating a supersaturated and supercooled state- the solution stays in the liquid form until a seed crystal, provided by clicking the metal disk, initiates the solidification. The resulting white crystal is actually quite hot; solid states have lower energy than liquid states and thus the difference in energy is given up as heat that raises the temperature back up to the melting temp, and you can see in the few seconds of the video that the temperature rises from 26C to 34C. This pack is reusable many times- just boil the pack until all the crystal is melted to reset. 

Drinking Bird Heat Engine

Get this famous physics toy from these sources: 
From Educational Innovations: BUY NOW 
Drinking Bird Engine 

From Amazon: BUY NOW 
Drinking Bird Engine 


Wikipedia has wonderful details about the rich history (and further descriptions of the operational principals) of the Drinking Bird
Drinking Bird Heat Engine: time lapse of 15 minutes into 15 seconds (4 cycles). Cooling by evaporation at the head leads to lower pressure in the top bulb, the dichloromethane fluid rises 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 time lapse allows a clearer picture of how the fluid rises, shifting the center of mass, and how tipping makes the glass column lift out of the fluid in the bottom allowing the pressure to equalize and letting gravity pull the fluid to return to the base. Process repeats as long as the top stays wet. So much physics in one hypnotic toy!

Hand Boiler

A variety of shapes and colors are available 
From Educational Innovations: BUY NOW 
Hand Boilers 

From Amazon: BUY NOW 
Hand Boilers 

Hand Boiler: liquid-gas phase transition. The boiling point of dichloromethane is slightly below body temperature - heat from a hand increases pressure in the bottom bulb pushing the purple (dyed) liquid through the glass pipe to the top.