All physicsfun toys

Stirling Engine

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From Amazon: BUY NOW Low Temp Stirling Engine 

Stirling Engine: low temperature difference engine turns a fraction of the heat of hot tap water into mechanical motion. For this engine the heat source is the hot tap water, and the heat sink is the room temperature air. Really nice model and super inexpensive for a display engine of this type.

Sprial Oil Drop Timer

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From Amazon: BUY NOW: Oil Drop Timers

Spiral Oil Drop Timer: when this drop timer achieves its steady state the drops form with amazing regularity in terms of both the size of the drop and the spacing between drops. The physics of immiscible liquids, surface tension, viscosity, and gravity combine to produce these interesting patterns. 


There are many affordable versions of this device: 
The original version is available here: 
From Amazon: BUY NOW 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. 

Mini-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 or in this case s segment of cord. This miniature version loops through itself nine times which requires the spring ribbon to twist creating a tension such that when released the spring will pop into its minimum energy state- a flower-like torus. Amazing combination of math and kinetic art invented by Jochen Valett. Thanks to Tim Rowett for sending me this rare mini version for my collection.

Precession of a Gyroscope

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From Amazon: BUY NOW Gyroscopes  

Precession of a Gyroscope: in defiance of gravity this gyroscope is supported only at one end. The physics and vector nature of angular momentum! Note that as friction slows the rotor of the gyroscope down, the precession rotation rate gets faster and faster. After some energy loss the gyroscope contacts the table and vibrations move the unit around while the angular momentum maintains its orientation. 

Fluorescence and Birefringence in Calcite

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From Amazon: BUY NOW Optical Calcite Crystal 

Need a UV laser pointer? Get 3 lasers (one of each color): 
From eBay: BUY NOW red+green+blue(UV) laser pointers

Fluorescence and Birefringence in Calcite: two samples of calcite- each with different impurities that produce blue fluorescence for the small crystal and red fluorescence for the larger one under a 405nm violet laser. Also one can clearly see that the single laser beam takes two paths through the crystals- the speed of light in a calcite crystal depends on polarization because the refractive index is different depending on the polarization orientation of the light transmitted through it.

Dual Axis Sand Pendulum

Available in many styles and colors: 
From Amazon: BUY NOW Sand Pendulum

Dual Axis Sand Pendulum: the kinetic energy trades back and forth between swinging toward the support arm and then swinging perpendicular to that path tracing Lissajous figures in the sand. The sand slowly dissipates the energy and the traced figures get smaller so the next one fits inside the last. Coupled oscillations like this can occur when multiple modes of motion (degrees of freedom) are available to the system.


From Amazon: BUY NOW Magswitch 60 
Here is a nice description of how such switchable permanent magnets work

Magswitch: switchable permanent magnet- a twist of a knob turns on a magnetic field strong enough to lift this 5.2 kilogram (11 pound) chunk of railroad rail. Magnetic fields, when combined, can be either additive or subtractive. This Magswitch model, the Magjig 60, works by aligning and counter-aligning two strong neodymium dipole magnets within a field channeling ferromagnetic casing.

Surfs Up Wave Machine

This Simpson's themed wave machine was made back in 1999-2000 and is hard to find. Here is a fairly inexpensive wave machine that has a similar base mechanism: 
From Amazon: BUY NOW Liquid Wave Machine

Surf's Up Wave Machine: Bart rides a surfboard between two immiscible liquids which are sorted under gravity by density with the densest (dyed water) on the bottom and the lightest (mineral oil) on top. Bart’s board has a density between that of the two liquids so it stays at the boundary layer, and a capsule of air above Bart’s head keeps him upright. The motorized rocking mechanism in the base is powered by one C cell battery and produces the waves at the boundary layer by sloshing and colliding the dense liquid off each end. Found this rare 1999 toy on eBay.  

3D Pentominoes

The set I used for this video is called Pocket Katamino and is available here
From Amazon: BUY NOW Pentominoes 

3D Pentominoes: the 12 possible arrangements of five identical squares, joined edge to edge, form the set of all pentominoes. Since 12x5=60, the pentominoes can tile a 6 x 10 rectangle with no gaps (2339 ways to do this- yet even finding one solution is a challenge). This set of colorful pentominoes is made so that the height of each piece is the same as the width of the constituent squares, such that 3D constructions can be made. Since 3x4x5=60 one can build a box with these dimensions (amazingly, 3940 ways to do this- but again, finding one is still a fun challenge). 

Switch Pitch Ball

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From Amazon: BUY NOW 
Switch Pitch


Switch Pitch Ball: this spherical assembly changes color by turning inside out when tossed into the air. Advertisements for this toy incorrectly claim air drag is involved in the transformation. 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.

Spin Bank

Available from these fine sources: 
From Amazon: BUY NOW 
Coin Spin Bank 

Spin Bank: a clever spring mechanism launches each coin into rotation along a symmetry axis on to a concave trapping surface. Angular momentum of the spinning quarter keeps it upright even as it bounces upon impact with the platform. Another spin on making saving spare change fun!

Giant Newton's Cradle

Regular sized Newton's cradles availabe here:
From Amazon: BUY NOW: Newton's Cradle

Newton's Cradle: industrial model made with galvanized aircraft cable, aircraft aluminum for the frame, and 1.5 inch one-half pound nickel plated chrome steel spheres. (0.23 kg and 3.8cm in diameter each) The classic demonstration that shows the curious behavior due to conservation of both momentum and kinetic energy. Swipe to see comparison to standard version.