Budget physics

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.

Mini-Lollipopter

Available here:

From Amazon: BUY NOW: Lollipopter Kinetics

From eBay: BUY NOW: Lollipopter Kinetics

Mini-Lollipopter: new smaller cousin of one of my favorite interactive kinetic sculpture designs. A snap of the wrist imparts angular momentum to the "petals" which then rotate until an internal mechanism stops their motion with predetermined spacing- clockwise rotation transforms a helix to an abstract pine cone, counterclockwise returns the helix. Created by @john.edmark.


WindGyro

Get one here!

From Educational Innovations: BUY NOW: WindGyro

WindGyro: Spin this top up with a puff of air! Small magnets keep the top secured to the base so that a stream of air will induce rotation as the air flows through the engineered turbine blades of the elegant spiral structure. 


Thermochromic Safety Sticker

These stickers transition back and forth and can be used on many surfaces. Get some here:

physicsfunshop: 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

Magnetic Sand Hourglass

Get one from these fine sources: 
From Educational Innovations: BUY NOW Magnetic Sand Timer 
From Amazon: BUY NOW Magnetic Hourglass 

Magnetic Sand Hourglass: 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, creating interesting patterns that reveal the magnetic field lines. 

Cartesian Diver

Glass divers available here: 
From Amazon: BUY NOW Glass Divers or this complete set Cartesian Diver Kit

Inexpensive and fun diver kits to make in a bottle available here: 
From Educational Innovations: BUY NOW Cartesian Diver Kits 

Wikipedia has the details on the Cartesian diver (and reverse diver)

Cartesian Divers: increasing pressure on the water compresses the air bubbles in the small glass vials filling them further with water making them sink. Pascal's principle states that any change in pressure on an enclosed fluid (such as pushing on the rubber cover) is transmitted evenly to every part of the fluid- the physics of hydraulic brakes! Named after the physicist and philosopher Rene Descartes.


Time's Up

Similar timers available from these sources: 
From eBay: BUY NOW 
Inverted Timer 


From Amazon: BUY NOW 
Inverted Timer 


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. 

Switch Pitch Ball

Many colors to choose from- get one here: 
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.

LASER Pointers + Diffraction Grating

Need a laser pointer? Incredibly, you can get 3 (one of each color) for under $20 (including S&H): 
From Amazon: BUY NOW Red+Green+Purple Laser Pointer

Rainbow Symphony has a nice selection of diffraction gratings and sun catchers:
From Amazon: BUY NOW: Diffraction Grating Toys

LASER Pointers + Diffraction Grating: three frequencies of laser pointer- Red (635 nm), Green (532 nm), and Blue (450 nm). Note that the distance between the intensity maxima (bright spots) is greatest for the red (long wavelength) and closest for blue (shortest wavelength) with the green in between. The diffraction grating is the same form as one of those rainbow fireworks glasses- this one from has 13500 lines per inch. 


Balance Pteranodon

Get one here! 
From Amazon: BUY NOW Balance Pteranodon 
From eBay: BUY NOW Balancing Pteranodon

Balance Pteranodon: 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 Wind Turbine

Nice little unit for the price! 
From eBay: BUY NOW Mini Wind Turbine 
From Amazon: BUY NOW Mini Wind Turbine 

Mini Wind Turbine: self-contained miniature horizontal axis wind turbine generates enough power to light three LEDs. A small turbine blade is attached to the rotor of a tiny generator that powers the LEDs. Conversion of energy- wind kinetic energy to rotational kinetic energy to electrical energy to light energy. I like how the wind vane and tower are also designed from acrylic as light pipes for the LED light. A fun little toy that demonstrates the physics of renewable energy!

Homopolar Motor

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!


Backflipping Wind-Up

Get a Back Flip wind-up toy here:

from eBay: BUY NOW: Uglydoll Backflipping Toy

from Amazon: BUY NOW: Backflipping Wind Up Toys

Backflipping Wind Up: an energy transfer toy- a wound coil spring transfers and stores energy through a set of gears to a straight spring which is suddenly released to create kinetic energy which is then converted to gravitational potential energy- sending the toy air bound into a back flip. Here the Uglydoll character Is made of clear plastic allowing the internal mechanism to be visible. In addition the feet of the character must push off with just the right rotation rate to allow for one full rotation in the air, and the tail has a foam pad to absorb the impact and stop the rotation. A lot of fun physics to consider in this toy.

 

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. 

 

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.