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.
Get this nice example of mystery braid here:
From Art of Play: BUY NOW: Impossible Braid Key Fob
Here is a great video on how to make the mystery braid
See other Impossible Objects in my collection.
Mystery Braid: challenge- how can three strands be braided if both sets of ends are connected? (swipe for reveal) A new addition to my collection of “impossible objects”, this leather key fob is braided from a single piece of leather, constructed by making two parallel slits but not cutting the ends. The solution is well known to those in the field of leatherwork- due to a twist of topology it’s possible to make this braid if the number of left strand over right crossings equals the times the right strand crosses over the left. Four strands braided this way is not mathematically possible, but 3, 5, or any odd number can be done!
Get this super nice, affordable, and fun to assemble kit here:
From KiwiCo: BUY NOW: Glow Pendulum Kit
Get amazing quatilty science kits delievered to your home- this glow pendulum is part of the Tinker Crate subscription.
From KiwiCo: LEARN MORE: Tinker Crate Subscription
Glow Trace Chaotic Pendulum: this fun and amazing DIY kit features a UV diode to trace the intricate path of this double pendulum system on to a phosphorescent screen, revealing the physics of chaotic motion. It’s amazing that such complex motion can arise from a simple assembly of two pendulums, one attached to the end of the other. Chaotic motion, such as that observed here, is characterized by extreme sensitivity to initial starting conditions, tiny differences in how the system is released leads to dramatically different outcomes each time.
Neodymium magnets will produce the largest gap when suspending a nail.
Please use exterme caution when handling these magnets.
From Amazon: BUY NOW: Neodymium Super Magnet
Magnetic Defiance of Gravity: a nail suspended between a chain and a powerful neodymium magnet. Ferromagnetic attraction over a distance of many millimeters, and a reminder of the presence of the typically invisible electromagnetic forces all around us. Make your own with a paperclip, string, and a refrigerator magnet- or get a neodymium magnet and see how massive an object you can suspend in air.
I used neodymium disk magnets, small end = 1/2" diameter, Large end = 3/4" diameter.
From eBay: BUY NOW Disk Magnets for Simple Motor
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.
All the ingredients are available from your local market/drugstore. The trick is to find a dye that works for acetone, but will not color water- believe it on not blue glitter will color the acetone nicely and not change the salt water. Follow this link for details:
ChemEd X: Blog of Prof. Tom Kuntzleman
Of course Amazon has what you will need:
From Amazon: BUY NOW
acetone, blue glitter, food coloring, cool bottle
Salt Fractionation: two liquids that won’t stay mixed! Acetone (dyed blue) floats on top of the higher density salt water (dyed orange). Acetone usually dissolves in water through hydrogen bonding interactions, but solubility can be altered. In a process called “salting out” a sufficient amount of salt is dissolved such that the water molecules, which are much more attracted to the resulting Na+ and Cl- ions (through ion-dipole bonds), will then ignore the weaker acetone hydrogen bonds. This results in the spontaneous separation (shown here in real time) of the liquids no matter how well shaken up.
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!
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.
The bottle used here is from Voss Water: a nice cylinder and the labels come off easily. Amazon has the ingedients:
From Amazon: BUY NOW
acetone, blue glitter, food coloring, Voss Water
The density column I made for this video is based on blend of two ideas: this "science snack" from the exploratorium: Klutz-Proof Density Column and this ChemED X post: Blog of Prof. Tom Kuntzleman
See my Salt Fractionation post for details.
Unmixing Density Column: three liquids that won’t stay mixed! Acetone (dyed blue) floats on top of the higher density vegetable oil, which in turn floats atop salt water (dyed orange) which is more dense than oil. Acetone usually dissolves in water through hydrogen bonding interactions, but solubility can be altered. In a process called “salting out” a sufficient amount of salt is dissolved such that the water molecules, which are much more attracted to the resulting Na+ and Cl- ions (through ion-dipole bonds), will then ignore the weaker acetone hydrogen bonds. This results in the spontaneous separation of these three liquids no matter how well shaken up.
Get this kit here (comes complete as shown in my video):
From engineDIY: BUY NOW: Magnetic Levitation Module
The featured sculture is by Bathsheba Grossman, affordable and beautiful math art available here:
From Etsy: BUY NOW: Soliton Sculpture
Electromagnetic Levitation Module: this engineered control system uses adjustable electromagnets (four copper coils) and and two Hall effect magnetic field sensors (held firm embedded in white silicone) to levitate an 5cm diameter neodymium magnet platform about 3 cm in mid-air. A feedback loop informed by the Hall effect sensors allows fine tuning of the magnetic field to exactly balance the pull of gravity, and is powered by a standard USB connection. The platform also rotates, perfect for showcasing one of my metal 3D printed mathematical sculptures by Bathsheba Grossman.
These aluminium 1 Yen coins are the perfect denisty to float as shown in the video:
From Etsy: BUY NOW: 1-Yen Coins (20)
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.
Just thread a rubber band through two of these drilled steel balls and you are ready to go!
From Amazon: BUY NOW
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.
Here are disk magnets I used for the "wheels":
From eBay: BUY NOW Neodymium Disk Magnets
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
Self Propelled Homopolar Motor: cylindrical neodymium magnets supply the static magnetic field for this motor and become the wheels of a very simple vehicle with an AA battery as the energy source. As soon as both ends of the copper wire make contact, an electric current will flow which in turn induces a magnetic field around the wire. This induced field around the copper wire will then interact with the neodymium magnets on each end causing them to spin- a wonderful example of a motor with minimal components.
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.
The DIY version can be assemebled with these parts. Steel wire of guage 10 or 12 should work well.
From Amazon: BUY NOW: Quilting Hoop, Neodyumium Magnet, Steel Wire
Magnetic Hoops Suspension Sculpture: Steel circles are suspended by a magnet (black sphere) and held down to the base by a thin thread. The tops of the steel hoops, being ferromagnetic, become a north pole in the presence of the south pole end of the black magnet, so they are attracted to the black magnet, but repel each other. Made by Rathcon Inc. in 1970. Swipe to see my DIY version made from a quilting hoop, neodymium magnets, and some bailing wire.
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.
Amazon lists acrylic tubing at a reasonable price: get a 2 foot long tube with an inner diameter of 1.5 inches for about $17 US. This will accommodate a large marble for the demonstration.
From Amazon: BUY NOW Acrylic Tubing
For a 1.5 inch inner diameter (3.8 cm) tube you will need a 10 inch (25.4 cm) wide sheet to complete a cylinder inside the tube.
From Educational Innovations: BUY NOW Polarizing Film
Polarizing Filter Black Wall Illusion: two sheets of polarizing film (with polarization axes oriented at 90 degrees to each other) create this illusion inside an acrylic tube. Physics magic!