Budget physics

Ring Catch Chain Trick

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From Amazon: BUY NOW Ring and Chain Set 

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The physics of this trick in great detail with more slow motion: Ring Falling into a Chain: No Magic — Just Physics 

Ring Catch Chain Trick: a solid ring will be caught by a loop of chain if it tumbles during its fall. By Newton's Third law, when the ring twists into and hits the chain, the impact transfers momentum to the end of the chain, which rises up and over the ring- seen here in 480 fps slow motion. 

Hydrophobic Water Maze

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

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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.


Precession of a Gyroscope

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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. 

Thermochromic Liquid Crystal Mood Necklace

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Thermochromic Liquid Crystal “Mood” Necklace: heat from a hand brings out the temperature dependent color change of the liquid crystal. The molecules of the liquid crystal change orientation and spacing during the phase transition from liquid (warm) to crystal (cool). The molecular configuration shift allows for different diffraction effects producing the color shift. 


Top Secret

This physics toy top is available here: 

From Amazon: BUY NOW Mystery Spinning Top

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The amazing green magnetic viewing film is also available: 
From Educational Innovations: BUY NOW Magnetic Field Viewing Film 

Here is the 1974 patent showing the very simple circuit of this device. The spinning dipole (the top itself) induces a current in one of the coils, and this current is fed to the base of the transistor turning the electromagnet on when the top is near. 
 

"Top Secret": this top will stay spinning for more than a week- because it is actually a motor! The top is a dipole magnet (as revealed by Magneview film) and the base has an electromagnet that gives the dipole a push when the top comes near the center. An ingeniously simple circuit consisting of only a battery, a coil, and a transistor, is activated when the spinning magnet nears the coil turning on the electromagnet to give a boost to the spin of the magnetic top.

Acrylic Rattleback

These acrylic versions work great and are inexpensive: 
From Educational Innovations: BUY NOW Rattlebacks 
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Acrylic Rattleback: a favorite from my collection- 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 the asymmetric shape of the bottom of this kind of rattleback, it's somewhat propeller shaped with an "S" curve along the bottom ridge

Reaction Rocket

The essence of a great physics toy: simple inexpensive design showing complex physics 
From Educational Innovations: BUY NOW Reaction Rocket 

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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).


Oil Drop Timer

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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. 

Self-Propelled Homopolar Motor on Aluminum Foil Racetrack

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

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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.


Oil Drop Cascade

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Oil Drop Cascade: interplay of surface tension and gravity bend oil drops into strange shapes as they move through a grid of obstacles in this kinetic art toy. Like other oil drop timer toys, the colored oil will not mix with the clear kerosene liquid. 

Pixelated Playing Cards

Available from these fine sources: 
From Amazon: BUY NOW Pixel Cards 

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Pixelated Playing Cards: what one sees is all about the lighting with this transparent deck of cards. When backlit these poker sized cards become simply a grid of dots- reminding us that what we see not only concerns the physical properties of the perceived object, but also the location of the light source and the frequency and intensity of its emissions.

Well Balanced Cabernet

Similar wine racks available here: 
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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. 


Drinking Bird Heat Engine

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

Memory Spring

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From Mindsets: BUY NOW Memory Springs 

Affordable samples and kits here:
From Educational Innovations: BUY NOW: Energy Wire 

Similar produces featuring Nitinol Memory Wire: 
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Memory Spring: some special alloys of brass can be made to have a shape memory triggered by temperature. These springs quickly change their length from 1 cm to 2.5cm when heated above 90 C (done here with hot water) and just as quickly shrink back to original size when cooled (immersed in cold water). Useful in many applications, especially things like automatic fire sprinkler valves and thermostats in car engines. This amazing property is related to a solid state phase transition similar to that of Nitinol wire called a Martensitic transformation.

Time's Up

Similar timers available from these sources: 
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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.