Hyperbolic Holes
This inexpensive kit available here:
From Amazon: BUY NOW: Hyperbolic Holes Kit
Hyperbolic Holes: a straight rod, in this case a pencil, glides through a symmetrical pair of curved holes. The design is based on the hyperboloid, the 3D ruled surface traced by an offset rotating diagonal line. This device is sold as an inexpensive kit to assemble yourself, and includes a motor with geared drive and pre-cut pieces. The pencil is my addition- sharpened to just the right size to clear the curved openings.
Centripetal Spheres
Just thread a rubber band through two of these drilled steel balls and you are ready to go!
From Amazon: BUY NOW: Drilled Spheres
Centripetal Spheres: two ball bearings connected by a rubber band orbit each other as energy oscillates between elastic potential energy and rotation kinetic energy. Just wind up the rubber band and let go. When the rubber band has unwound the rotational inertia of the bearings winds it back up until it changes direction. The process repeats until the initial energy is dissipated through friction.
Super Absorbent Polymer
Get some of these grow-spheres here:
From Educational Innovations: BUY NOW Growing Spheres
Super Absorbent Polymer: poly-acrylamide polymer crystals are able to absorb up to 200 times their volume of water. Here seven small spheres, approximately 4mm in diameter, were immersed in water for three hours, after which they were slightly more than 23mm across. The final gel sphere is more than 99.5% water- and they bounce!
Floating Yen
Aluminium 1 Yen coins are the perfect denisty to float as shown in the video:
From Etsy: BUY NOW: 1-Yen Coins
Floating Yen: the surface tension of water is strong enough to suspend the aluminum coin, and a trapped column of air in a second glass can submerge a portion of the surface with the coin. The 1-Yen coin has just the right mass and density for this demonstration. One of my favorite DIY physics demonstrations.
Tumble Rings
I made this set of tumble rings from reading Martin Gardner's description in his famous mathematical recreations books- highly recommended:
From Amazon: BUY NOW Knots and Borromean Rings by Martin GardnerDescribes the Tumble Rings
From Amazon: BUY NOW Books on recreational math and puzzles by Martin Gardner Lots of physics and math toys in these pages!
Tumble Rings: the links in this chain are connected in a special way such that the top ring appears to tumble to the bottom- a compelling illusion!
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!
Faraday Train
Here's the parts to make your own:
From eBay: BUY NOW Neodymium Spheres 15mm
From Amazon: BUY NOW Bare Copper Wire 10 gauge
The wire used for the Faraday Train has to be bare- so make sure it does not have any kind of clear coating on it. The solid grounding wire sold at hardware stores works great.
Here is a nice description of the Faraday Train and the physics of its propulsion.
Faraday Train: two magnets, one battery, and a coil of bare copper wire are the simple essence of this self propelled craft. The magnets conduct electricity, thus when put in contact with the coil current will flow creating a solenoidal magnetic field in the vicinity of the battery, which in turn pushes on the magnets at each end of the battery moving the craft along. The spherical neodymium magnets used allows the craft to slide along the coil with minimal friction.
Electric Motor Build
Get an easy to assemble kit here (or just buy the replacement wire to build your own like in the video):
From Educational Innovations: BUY NOW Simplest Motor Kit
Electric Motor Build: One of the most important inventions consists of only three basic components as shown here: coil, magnet, and a battery with lead wire posts. The wire of the spinning coil has an insulating coating on it- and this coating is carefully scrapped off one side of the thin wire 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 current goes on and off depending on if the copper wire posts are in contact with the bare wire side (current on) or the part of the wire with the insulating coating intact (current off). When the current is off momentum keeps the rotation going until the next push. The physics of converting electric energy to rotational kinetic energy- and a fun DIY project!
Mobius Zipper
If you like this kind of math exploration I highly recommend this book by Matt Parker:
From Amazon: BUY NOW
Things to Make and Do in the Fourth Dimension
... and any of the books by Martin Gardner
From Amazon: BUY NOW
Recreational Math Books
The parts to make this are inexpensive- a great craft for kids. Sew on the velcro dots for best results:
From Amazon: BUY NOW: Nylon Zippers, Velcro Dots
Möbius Zipper: exploring topology with a bisecting strip (a zipper with velcro ends). 0 twists creates a cylinder which simply gives two cylinders when split, ½ twist creates a Möbius strip- splitting down the center produces one long loop with with two full twists, 1 twist in a loop-splitting in half produces two interlocked Möbius loops! Just some of the curious properties concerning the Möbius strip, an unorientable, one sided surface, with only one boundary.
Centripetal Kinetic Toy
This "iBall" desk toy is no longer in producltion. Howerver, a similar version of this toy can be made from these components:
From Amazon: BUY NOW: two piece acrylic shell
From Amazon: BUY NOW: 1/4 inch ball bearings
Centripetal Kinetic Toy: seven rolling steel balls hug to the inside of the acrylic sphere given sufficient velocity. Here the balls are launched such that their orbits are in the same plane, and due to their angular momentum (and a torque due to gravity) the plane of rotation precesses like the axis of a spinning top until friction slows them down. This toy was made in 2007 (sadly no longer in production) and marketed under the name "iBall".
Popsicle Stick Bomb
Craft sticke work great:
From Amazon: BUY NOW: Stick Bomb Supplies
Amazingly: There is a Wikipedia entry on Stick Bombs and their physics
Popsicle Stick Bomb: a form of simple tensegrity, the elastic potential energy of the bent sticks is dramatically released under application of a slight concussive force such as an impact with a table top- shown here in forward and backward slow motion (swipe to see three more explosions). Shown here is one of the simplest constructions with 5 flat sticks woven into a spring-loaded configuration held in place by friction and tension induced by the bending of the wood. A nice demonstration of energy conversion- potential to kinetic.
Micro Hoverboard
If you want to make one of these you will need:
1) some pyrolytic graphite (which can easily be sliced and carved):
From eBay: BUY NOW Pyrolytic Graphite
2) some neodymium magnets: the racetrack magnets are a bit pricey though!
From eBay: BUY NOW Diamagnetic Levitation Kit
3) shrink and print this image on medium weight paper,
and 4) cut and assemble!
Micro-Hoverboard: diamagnetic levitation technology- although Marty McFly would have to be three inches tall to ride this hoverboard. Made from printed paper and pyrolytic graphite with concentric circular neodymium magnet array. The magnetic rings alternate between north and south magnetic poles in just the right way to trap this special type of graphite. Pyrolytic graphite has strong diamagnetic properties such that it develops an opposite (but weak)magnetic field when in the presence of a magnetic field from another source. Swipe to see the graphite pieces levitating individually.
Bottle, Hoop, and Nail Trick
The hoop used is just the inner circle of an embroidery hoop. Get one for a couple dollars here:
From Amazon: BUY NOW Wooden Hoop
The science writer Martin Gardner has published many books of physics tricks and simple but amazing science experiments like the one in this video. Highly recommended.
From Amazon: BUY NOW Martin Gardner's Science Magic: Tricks and Puzzles
Bottle, Hoop, and Nail Trick: with some practice, a snap of the wrist removes the hoop and the nail falls straight into the bottle. Newton's 1st Law as seen in slow motion- a mass at rest tends to stay at rest. (Best to watch with sound/audio) Balancing the nail on the hoop ensures the nail is directly over the top of the bottle. The hoop is removed so quickly that it does not interact significantly with the sufficiently massive nail, and thus the nail remains over the mouth of the bottle so that gravity pulls it in. G4G Week repost- a favorite from Martin Gardner’s collections of physics tricks.
Spinner Fidget Trick
Click this link for a gyroscope that will perform the same trick!
Spinner Fidget Trick: defy gravity!- a trick to try with a fidget spinner you might have in a drawer somewhere. For the trick to work the spinner needs to have most of its mass far from the center (not all spinners will work)- and you may need to drill a hole down its center to attach an axle. This Spinpal spinner has three heavy steel spheres placed to maximize rotational inertia, that along with precision bearings, gives this fidget toy properties of a quality gyroscope. Give the spinner significant RPMs and it will suspend from, and precess around, a string! Thanks to @spinpal for sending me this a while back.
Curie Point Heat Engine
This DIY project is pretty easy to build. One half of one of these inexpensive magnetic necklace clasps will work well for the heated magnet.
From Amazon: BUY NOW: magnets for curie point engine
A full engine is available from my friends at Grand Illusions Ltd:
From GI LTD: BUY NOW: Curie Engine
Curie Point Heat Engine: when the magnet on the end of the wire heats up to a particular temperature (the Curie point) its magnetic field is temporarily lost until it cools. This engine design uses a second magnet to pull the swinging magnet back into the heat source once the magnetic field is reestablished. Repetition of this process creates mechanical motion as long as the heat source is fueled.
Hoberman Actuator with Sphere
The Actuator mechanism is out of production but can still be found on eBay, comes with power supply, Expandagon kit, and connecotors that snap on to a Hoberman Spjere.
From eBay: BUY NOW: Hoberman Actuator
The spheres are still in production and come in various sizes and colors:
From Amazon: BUY NOW Hoberman Spheres
Hoberman Actuator with Sphere: This actuator mechanism creates kinetic art out of a Hoberman sphere, designed to smoothly expand and contract the isokinentic structure. The Hoberman sphere itself is a special assembly of foldable linkages consisting of rigid bars and simple hinges is kinematically over constrained- motion can only occur along the radial direction and the movement of any hinge creates motion in all the joints. The engineering and physics behind deployable space structures!
Vibration Unthreading
Get inexpensive small motors and accesories for DIY projects here:
From Amazon: BUY NOW DC Motors Kit
A DIY project to see if just shaking a bolt at the right frequency could make a standard nut rotate and fall off. Similar physics to the phase locking propeller toy featured in my last post. Motivated by videos seen on Instagram where a brass bolt is placed in magnetic putty and the nut mysteriously rotates up and off- now convinced that vibration is how that effect is produced. Here a small DC motor spins an offset mass to produce the vibrations.
