Budget physics

Tail Spin Geared Kinetic Toy

Get one here: 
From eBay: BUY NOW: Tail Spin Kinetic Toy

Tail Spin Geared Kinetic Toy: fourteen gears arranged on seven linked segments meshed in such a way that the configuration can roll up and stack compactly or extend into a line. With a flick of the wrist, one can impart enough angular momentum to the assembly to cycle it through its full range of motion- shown also in 240fps slow motion at the end of the video. Invented by Oskar van Deventer and produced by Think Fun toys. 

 

Oil Drop Timer

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From Amazon: BUY NOW Dolphin Timer 

Oil Drop Timer with Dolphins: immiscible fluids of different densities stay separate under gravity with the lightest density on top. The density of the plastic dolphins is greater than the density of the top fluid but less than the density of the bottom fluid, so they stay at the boundary in equilibrium. The dolphins have a metal weight in their tails so that the buoyant force will keep them upright even as the liquids trade places (2 minutes shown in time-lapse). Archimedes' Principal at work here at multiple levels. 

Mini Balance Pterosaur

Get this mini prehistoric balance beast here: 
From Amazon: BUY NOW Balance Pterosaur

Mini Balance Pterosaur: 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. 


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.

Self-Propelled Homopolar Motor on Aluminum Foil Racetrack

I used neodymium disk magnets, small end = 1/2" diameter, Large end = 3/4" diameter. 
From eBay: BUY NOW Disk Magnets for Simple Motor 

Foil Runner Motor assembly diagram: 
Self-Propelled Homopolar Motor on Aluminum Foil Racetrack: A favorite DIY physics toy where disk shaped neodymium magnets supply the static magnetic field for this motor and become the wheels of a very simple vehicle with an AAA battery as the energy source. As soon as both ends make contact with the conducting aluminium foil an electric current will flow which in turn induces a magnetic field underneath the battery assembly. This induced field will then interact with the neodymium magnets on each end causing them to spin- a wonderful example of a motor with minimal components. The racetrack is a cardboard circle from a pizza box covered in kitchen foil.

Well Balanced Cabernet

Similar wine racks available here: 
From Amazon: BUY NOW 
Balance Wine Rack 

Many well crafted versions avaulable here:
From Etsy: BUY NOW 
Wine Bottle Balance

Acrylic Wine Bottle Balance

Well Balanced Cabernet: a carefully engineered acrylic version of this famous demonstration- the center of mass of the rack/wine bottle system is directly over the base providing unstable equilibrium for this balancing act. Suspended here is Hypothesis by Roots Run Deep, an excellent Napa cabernet sauvignon. 


Hydrophobic Water Maze

Wonderfully well crafted and available from this shop :
From Etsy store TheSmallestWorkshop:

BUY NOW Hydrophobic Water Maze

Hydrophobic Water Maze: a superhydrophobic coating allows this dynamic puzzle to use a drop of water as the "pinball", which can split into multiple smaller drops and recombine along the way. The wood surface is treated with silica nano-coating that makes water roll off- a condition sometimes referred to as the Lotus effect because leaves of the Lotus plant have this property.

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. 

 

Magnetic Top and Snake

Available in a variety of styles: 
From eBay: BUY NOW Magnetic Top and Snake 
From Amazon: BUY NOW Magnetic Top and Snake 

Magnetic Top and Snake: the magnetic tipped top stays on the perimeter of the steel snake (or is it a planarian?)- but since the top has much more mass, the snake moves the most slithering to and fro. This kinetic art toy has been around for decades and takes advantage of Newton's 3rd law and rotational kinetic energy. 


MaBoRun Minis

Many styles to choose from- get a MaBoRun here: 

From eBay: BUY NOW: MaBoRun Mini

Similar devices here:
From Amazon: BUY NOW MaBoRun Marble Run 

MaBoRun Minis: rolling marbles doing tricks as gravitational potential energy is converted to kinetic energy. Three mini marble runs each with a battery powered means of lifting the marbles: 1) a belt driven gear, 2) a scissor linkage that translates the rotation of the motor into linear motion to lift the marbles to the top and 3) an Archimedean Screw conveyer. Two of these runs incorporate a simulation of decaying orbits with conservation of angular momentum as the marbles whirl down funnel shaped tracks.

Animallusions Zebra

Get this illusion here: 

from Amazon: BUY NOW: Animallusions Zebra
or here: Illusion Animals

The original DIY dragon from G4G 3: Dragon.pdf

Animallusions Zebra: an amazing version of the hollow face illusion where the zebra’s head appears animated, and gives the impression that it’s always looking in the direction of the viewer. This zebra seems inspired by the dragon illusion created for the 1998 Gathering for Gardner by the Binary Arts Corporation of Bill Ritchie et al. Some fun physics of perspective and psychophysics for your shelf.


Tornado Spheres

Get a set here: 
From eBay: 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).

Drinking Dino Heat Engine

This dinosaur themed heat engine available here:

From Amazon: BUY NOW: Drinking Trex Desk Toy

Get also: the related Drinking Bird Heat Engine 

Drinking Dino Heat Engine: So what physics presents did you get this year? I got this Dippy Dino heat engine- where cooling by evaporation at the head leads to lower pressure in the top bulb such that the dichloromethane fluid (colored green) rises up the neck making the T-Rex top heavy and the dino tips over dipping its face in the water and letting the fluid return to the bottom bulb. The process repeats as long as the top stays wet. A fun and silly variation on the famous drinking bird physics toy- and the T-Rex was a closely related ancestor to the dinosaurs that live today- birds! 

Mirascope

Similar devices available here:
From Educational Innovations: BUY NOW Mirascope 
From Amazon: BUY NOW Mirascope 
 

Mirascope: two parabolic mirrors create a 3D image above the actual object. A repost of one of my favorite physics toys ever. The image of the dice made here is not a hologram and is produced solely by reflection of light rays between special concave mirrors. Discovered circa 1969 by Landry and Elings at UC Santa Barbara.


Spinnobi Springy Spinner 

Get one here! 

From Amazon: BUY NOW: Spinnobi Spinner

Spinnobi: a spinner with bounce! With springs mounted along the axis on both sides of the dense rotating silicone disk, this spinner demonstrates gyroscopic stability- keeping its orientation as it falls and bounces. Conservation of angular momentum on display with this new take on the spinner.

Floating Yen

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

From Etsy: BUY NOW: 1-Yen Coins (20)

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.

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!