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.
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.
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!
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.
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.
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.
Available in four colors and designs:
From the @physicsfun collection: BUY NOW: Glass Water Tops
Glass Hydro-Top: under centripetal acceleration a liquid will flow to create a cylindrical surface parallel to the axis of rotation. This blown glass dreidel contains a small amount of colored water that when spun resembles a blue gemstone banded around the rim. A unique design with fun physics!
These acrylic versions work great and are inexpensive:
From STEMCell Science: BUY NOW: Rattlebacks
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
Get the full version (8 disks made of wood) or the mini (6 disks, blue or red plastic):
From Amazon: BUY NOW TrueBalance Coordination Puzzle
TrueBalance: coordination challenge puzzle- get the six disks, connected by bearing swivels, into a vertical stack by only tilting the handle. Harder than it looks to get each disk’s center of mass above the one below at the same time into the unstable equilibrium final state. The swivels constrain the system, limiting the degrees of freedom, and allowing strange and interesting motion. Kinetic art as a toy!
Similar mood jewelry available here:
From Amazon: BUY NOW Liquid crystal jewelry
Neclace featured in video: Earthbound Trading Co
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.
Get one here:
From Amazon: BUY NOW Balance Bird
Balance Bird: weights in the wing tips create a center of mass below the bird's beak- making a system in stable equilibrium. No magnets!
Get some of these grow-spheres here:
From Educational Innovations: BUY NOW Growing Spheres
Poly-acrylamide Polymer Vanishing Act: these spheres of hydrophilic polymer have an almost identical index of refraction as that of water- thus when submersed they become invisible. Note the elasticity of these spheres from the way they bounce, while at the same time they refract their surroundings as a spherical lens. The super absorbent spheres start as hard crystals with a radius of 2mm and grow to 11mm when immersed in water. So much physics going on here!
Get this famous physics toy from these sources:
From Educational Innovations: BUY NOW
Drinking Bird Engine
From Amazon: BUY NOW
Drinking Bird Engine
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!
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!
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.
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.