The essence of a great physics toy: simple inexpensive design showing complex physics
From Educational Innovations: BUY NOW Reaction Rocket
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).
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From Educational Innovations: BUY NOW Polydensity Bottle Kit
Folow the link above for details of the physics explanation.
Poly Density Puzzle: my favorite science brain teaser- white beads and blue beads "float" oddly separated beneath the surface of a clear liquid. If the contents are mixed by shaking the container, the white beads gather at the top and the blue sink to bottom! Adding to the mystery; after about 30 seconds the two layers of beads will have slowly moved back to the middle. What is your guess as to the physics behind this behavior?
Get a PhoTOP from these fine vendors (comes with laser pointer!):
From Educational Innovations: BUY NOW PhoTOP
From Vat19: BUY NOW: PhoTOP
Another amazing spinning device by Prof. Ken Brecher! Get his other spinning tops here:
From Etsy: BUY NOW: PhiTOP, PiTOP, eTOP, iTOP, DeltaCELT
The PhoTOP: phosphorescent glow illuminates the intricate path of a 405nm laser pointer beam on a balanced spinning disk. Let the disk set alone for a few minutes to allow the traces to fade- and repeat again and again to experiment making new patterns.
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 one here! Chose your color scheme and length, all come with the special motor and operating instructions:
From Educational Innovations: BUY NOW: Dancing Helix
The Dancing Helix: This kinetic mobile's mesmerizing motion arises from pulsed torsion waves that propagate up and down the length of a series of weighed rods connected by an elastic ribbon (which acts as a torsion spring). The waves arise by a special pulsed motor from which the strand hangs, and only spins for a second or so out of each minute. The twisting waves then constructively and deconstructively interfere creating an array of flowing motions.
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From Educational Innovations: BUY NOW Newton's Yoyo
Newton Yo Yo: Newton's 3rd Law states that action force equals opposite reaction force- the the green and yellow spheres have equal mass, so the forces of the collision provide accelerations that are equal and opposite such that the spheres trade places.
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From Educational Innovations: BUY NOW Melting Snowman Kit
Viscoelastic "Melting Snowman": non-newtonian flow is demonstrated by these blobs of viscoelastic silicon polymer (aka Silly Putty) in the shape of snowman- if force is applied over a short period of time the substance shows elastic properties (bounces like a superball), but if the force is applied slowly the substance flows like a viscous liquid (flattens under gravity over a few hours as shown here). Thus this snowman does not melt because it is already liquid, one that flows slowly though. Mostly sold as a toy, Silly Putty was discovered after mixing boric acid with silicone oil during World War II in an attempt to find a rubber substitute.
Get this easy to assemble kit here:
From Educational Innovations: BUY NOW Simplest Motor Kit
Electric Motor: in its simplest form!- coil, magnet, and battery. The wire of the coil has an insulating coating- and this coating is carefully scrapped off one side on each end. When current passes through the coil it becomes an electromagnet and the permanent magnet repels it making it spin- as it turns the currents goes on and off depending if the copper posts are in contact with the bare wire (current on) or the still insulated wire (current off). I have motors with fewer parts- but they operate on more complex principles.
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From Educational Innovations: BUY NOW: Happy/Sad Balls
Happy/Sad Spheres: one ball bounces the other stops dead. The bouncy ball is made of neoprene rubber and exhibits high elasticity. The "sad" ball is made of polynorbornene and converts almost all kinetic energy into heat and sound- approximating/demonstrating the case of a completely inelastic collision. Polynorbrene is used in vehicle bumpers, for soundproofing, vibration damping, and other applications where recoil motion is unwanted.
Many colors (and two sizes) to choose from:
From Educational Innovations: BUY NOW
From Amazon: BUY NOW
The physics of the liquid rope-coil effect is pretty complex. Here is a recent scientific paper on the topic with nice illustrations.
Journal of Fluid Mechanics: Multiple coexisting states of liquid rope coiling
Ooze Tube: viscous polyisobutene fluid timer toy. Some interesting physics phenomena are found in this kinetic art novelty item: the "liquid rope-coil effect" where the fluid thread coils and stacks as it lands on the pooling surface, and a curious periodicity in the rate of flow that is related to the formation of non-spherical bubbles as the air and fluid trade places (shown in time-lapse). The physics of the coiling effect is complex (see the link in my blog). Broadly speaking the coiling is due to the bottom of the fluid rope widening at the contact point with the surface, and as it widens the fluid slows down but not evenly. This uneven rate of flow produces a bend and the elasticity of the stream constrains the rope to a limited radius- hence a stack of coils.
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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.
Here is an affordable version of this device:
From Educational Innovations: BUY NOW Flow Ring
The original version is available here:
From Amazon: BUY NOW Toroflux
Get one and flow with it!
From Art of Play: BUY NOW
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.
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, segment of tubing, or even an arm. Amazing combination of math and kinetic art invented by Jochen Valett.
Get one here!
From Educational Innovations: BUY NOW PhiTOP
From Amazon: BUY NOW PhiTOP
The PhiTOP: spinning things often have surprising physics! This unique top is made of solid aluminum in the shape of a prolate elIipsoid- and the name of the top is derived from the following design requirement: the ratio of the semi minor (short) axis to the semi major (long) axis is made equal to the mathematical constant the golden ratio φ (phi). Invented by astrophysicist Kenneth Brecher, this top stands up vertically (when spun with sufficient rotational velocity) due to physics similar to that of the tippy-top.
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.
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From Edicational Innovations: BUY NOW: Switch Pitch Ball
Switch Pitch Ball: this spherical assembly changes color by turning inside out when tossed into the air. A favorite of my mechanical toys with surprising physics. Interestingly the advertisements for this toy incorrectly claim air drag is involved in the transformation. To understand why the ball inverts first note that 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.
Get a similar kit here:
From Amazon: BUY NOW Eddy Current tubes
Get some magnetic viewing film here:
From Educational Innovations: BUY NOW Magnetic Viewing Film
Lenz's Law: a strong neodymium magnet falls slowly down a copper bus bar as though passing through a viscous liquid. Since magnetic fields pass through copper, magneview film reveals the location of the falling dipole magnet. Moving magnetic fields from the falling magnet produce electric currents in the copper. These currents then produce magnetic fields that have the opposite polarity to the initial field. So a falling magnet makes the copper pipe briefly into an electromagnet that repels the magnet. The rectangular copper “pipe” is from a water-cooled electromagnet power supply line, 1.5 x 2 in (4 x 5 cm) in cross-section, designed to supply a steady DC current of 5000 amps. This 40cm long piece weighs in at 6kg and has a 1.5cm diameter hole for cooling water to flow down its center. From a decommissioned particle accelerator magnet.
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.
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From Educational Innovations: BUY NOW Magnetic Sand Timer
Magnetic Sandglass: 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 as they attempt to align with the magnetic field lines. These stacks topple over due to gravity creating interesting patterns.