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!
Similar timers available from these sources:
From eBay: BUY NOW
From Amazon: BUY NOW
Time's Up: inverse of the sandglass- tiny plastic beads are less dense than the water and thus ascend to the top of the container under the influence of a buoyant force in accordance with Archimedes' principle. This timer takes almost exactly 6 minutes to complete shown here at normal speed for the first half of this video, and the second half is condensed to 24 seconds in time-lapse.
Get one here:
From Amazon: BUY NOW Infinity Tea-Light
From eBay: BUY NOW Infinity Candles
Infinity Mirror Tea-light Candle: parallel partially mirrored panes of glass create the illusion of multiple candle flames through the physics of reflection and refraction. Featuring candles from my collection this month as the winter solstice approaches.
I made this device from these components:
From Amazon: BUY NOW: heavy guage copper wire (for frame), inexpensive necklace chain (for connections), and hobby wire (to fasten chain to copper frames).
Check out these other Tensegity toys I've posted.
Tension Suspension: an interesting take on tensegrity where one heavy wire frame seems mysteriously suspended above another. This sculpture features strings (chains used here to make it look more dramatic) in tension equilibrium, with the top wire frame hanging from the bottom frame by the strand in the center, and the other three strands in tension to keep it from tipping over. This configuration is related to the concept of tensegrity invented by Kenneth Snelson and made famous by the architect Buckminster Fuller in 1949.
These fountains are individually made by the artist hence they are priced as art reflecting the labor involved:
From Etsy store of Stephen Co : BUY NOW
Aquarius Fountain Lamp
Aquarius Fountain Lamp: an oscillating stream of water is illuminated by strobe lights to reveal underlying structures and forms typically hidden from our vision. With the help of programmable micro-controllers, strips of addressable RBG LEDs are made to flash in sequences that make the water stream appear to move upwards, change colors, and split into multiple braided streams. Art meets physics and clever technology in this wonderful creation by computer engineer Stephen Co. With sincere appreciation to Stephen @northerncircuits for sending me one of his hand crafted high tech fountains.
These vintage clocks are sometimes found on eBay. Some take 24 hours to descend (affordable) and some take 7 days (expensive).
From eBay: BUY NOW: Incline Gravity Clock
Ancient Clockwork Zamberlan posted theses nice photos of the inner workings of this clock
Incline Gravity Clock: powered by gravity this clock has no batteries or mainspring- however, once each day the clock must be picked up and placed back at the top of the ramp. As the clock rolls down the incline (here 12 hours are captured in time-lapse of 24 seconds), gravitational potential energy is translated into the kinetic energy of the moving clock gear train and oscillating balance wheel. The clock face and mechanism hang suspended with a counterweight that keeps them upright- although you might notice the mechanism of this vintage clock sticks a little at 7 o’clock. After some research I believe this clock was produced in China about 50 years ago.
From eBay: Search NOW: Coin Escape Puzzle
From Amazon: BUY NOW: Coin Escape Puzzle
Another coin escape puzzle (fits US Dollar), the YOT:
From Amazon: BUY NOW
Silver Dollar Escape Puzzle
Coin Escape Puzzle: physics brain teaser- remove the coin without breaking the container or using any tools other than your hands. Of course you spin it to get the quarter out- but exactly how? The solution to this puzzle (like others featured here) relies on some fun basic physics of spinning things. Answer below and swipe to reveal solution.
One of many creative illusions and curiosities of Victoria Skye. See her work here:
Visit Now: Victoria's Illusion Art
Click here for to explore more "impossible objects"
Impossible Arrow: an arrow made of wood through the center of standard steel hex nut. The arrow was carved and somehow placed through the nut- neither the wood nor the steel nut was cut or glued to produce this object. Not impossible, but creating this does depend on the use of some obscure physical properties of wood (similar to the impossible nail sculpture).
These type of objects were invented by mathematician Kokichi Sugihara, and you can buy his other books here:
From Amazon: BUY NOW Ambiguous Objects by Kokichi Sugihara
Also available from Amazon (Japan): BUY NOW set of four ambiguous objects with booklet
Similar objects available here- from Etsy: BUY NOW: Ambiguous Objects
Another illusion design by Kokichi Sugihara of Meiji University in Japan, the inventor of this illusion and art form. A mathematically calculated combination of perspective and the physics of reflection produce this striking illusion that works in many configurations.
Available for all the planets and several versions of Earth:
From Amazon: BUY NOW Mova Globes: all types
From Amazon: BUY NOW Mova Globes: Jupiter
From eBay: BUY NOW Mova Globes: all types
From movaglobes.com: BUY NOW Mova Globe: Jupiter
Jupiter Globe by Mova: rotating counterweighted globe sealed within a clear liquid filled acrylic sphere. The rotation is powered by light that shines through the semi-transparent Jupiter globe on to solar cells within the globe which drive a motor. But what does the motor push against to maintain the rotation? Believe it or not it uses magnets to push against the Earth's magnetic field like a compass needle. Wonderful physics of all kinds in the design of this clever device.
Vintage (1970s) Kalliroscopes are sometimes available here:
From eBay: Search NOW Kalliroscopes
Click this link for the best Kalliroscope currently in production and available.
Kalliroscope with Heating Element Stand: visualizing the invisible- convection currents. This wonderful vintage device was invented and produced by artist Paul Matisse in the 1970s, where suspended microscopic flat crystals of guanine reflect light and allow visualization of the fluid's motion. This rheoscopic fluid is special in that the guanine crystals are the same density as the tetrachloroethylene liquid so the crystals never settle to the bottom making the fluid reactive to showing the slightest movement. Here the stand option (that was sold separately) has a resistive element in contact with the back of the kalliroscope which generates heat at about body temperature to establish these convection currents.
This magnetic version fo Newton's cradle is no longer in production, but somtimes found on ebay:
From eBay: Search NOW: Magnetic Newon's Cradle
Here are some nice versions of the classic Newton's Cradle
and here is a nice Magnetic Replusion Demonstration
Magnetic Newton's Cradle: the famous collision demonstration reimagined with opposing magnets as the pendulum weights- shown here in two modes of operation. Initially the collision pattern looks similar to the traditional colliding spheres version but quickly goes chaotic- the magnetic field of each weight interacts with all the other magnets simultaneously making the system nonlinear. A 1990s desk toy by Fascinations- sadly no longer in production.
The best Klein Bottles are made by Cliff Stoll, astronomer, mathematician and artist. Every one-sided, zero volume bottle is packaged and shipped by Cliff himself. Get one today!
From ACME Klein Bottles: Buy NOW Klein Bottles by Cliff Stoll
Wikipedia has great details on the Klien Bottle, and the amazing Cliff Stoll.
The Klein Bottle: 3D representation of a four dimensional mathematical object with one side, no edges, and zero volume. Kind of like a Möbius strip with no edges.* Math meets glass art! Many thanks to Cliff Stoll for this kind gift and a great visit including a wonderful tour of his collection of mathematical oddities. *only achievable in 4D.
Samples available here:
From Educational Innovations: BUY NOW Ironwood Samples
Buoyancy Discrepant Event: wood that sinks and a rock that floats!- a study in density properties of ironwood and pumice.
The amazing work of Emmanuel Péluchon can be purchased here:
From Boisselier.ca: BUY NOW: Fine Woodworked Rattleback
Inexpensive rattlebacks can be found here:
From STEMCell Science: BUY NOW: Rattlebacks
Woodwork Rattleback: prefers to spin counter clockwise- If spun clockwise, a complicated combination of friction, precession, and instability induced vibrations transforms the rotational energy into into rattling (energy of oscillations) and then into rotational energy in the opposite direction. This behavior is related to an asymmetry in weight along the left/right symmetry axis- the dark wood is Apple which has twice the density of the light colored Basswood(Linden). This asymmetry in weight induces an instability, quite like the vibrations that arise from an unbalanced tire, that transfers the rotational energy to the intermediate rocking vibrations. This beautiful physics toy was produced by Emmanuel Péluchon.
From Art of Play: BUY NOW : Shashibo Geometric Art
Shashibo Geometric Art: dissect a cube into 12 equal irregular tetrahedra, connect these pieces symmetrically with hinges, and add 36 magnets to create a device with more that 70 geometrically interesting and aesthetic configurations.
These stickers transition back and forth and can be used on many surfaces. Get some here:
From StemCell Science: BUY NOW: Thermochromic Saftey Sticker
Thermochromic Safety Sticker: the liquid crystal ester dye in this reusable sticker is calibrated to change color when the surface temperature exceeds 50°C (122°F)- that at which prolonged contact (more than 0.5s) will burn skin. Here the safety sticker is attached to a slab of aluminum and heated with a simple candle- it took about 3.5 minutes for the heat to distribute and bring the aluminum to the threshold temperature. When the surface cools the sticker again appears blank and can transition over and over again