DIY

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. 

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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! 


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. 

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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.


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. 

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.

3D Print Planetary Gearset

The .stl files are available here:

From Thingverse:

Origial desing by Emmett Lalish Download: Gear Bearing 

Refined version featured here by Don Stewart Download: Honeycomb Gear Bearing 

Similar prints available as fidget toys here:

From Etsy: BUY NOW: Gear Spinner Fidget Toy

3D Print Planetary Gearset: amazingly this gear set is printed assembled, with interlocking herringbone teeth. The gears will not come apart, in fact this design can only be accomplished by 3D printing the gears interlocked with each other. Designed and first printed by Emmett Lalish in 2013, and this version with refined precision and honeycomb by Don Stewart. 


Floating Rings Illusion: Dr. Manhattan Booth

Created in my shop with these parts:

From Amazon: plastic rings, plastic sphere, blue paint

Inspired by the Phone Booths in the new Watchmen series.

Calling Dr. Manhattan: floating rings illusion device inspired by the recent Watchmen series. Two attached rings appear to roll in an impossible way around an orb, featured in a number of scenes on top of blue interplanetary phone booths in the new Watchmen series. Created in my shop with plastic rings and some blue spray paint. 

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. 

Magnetic Suspension Sculpture

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. 


Electric Motor

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.

Impossible Braid 

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!

 

 

Polarizing Filter Black Wall Illusion

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!


Floating Yen

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.

Ring Catch Chain Trick

Get a set here: 
From eBay:(best selecton) BUY NOW Ring Chain Catch 
From Amazon: BUY NOW Ring and Chain Set 

The physics of this trick in great detail with more slow motion: Ring Falling into a Chain: No Magic — Just Physics 

Ring Catch Chain Trick: a solid ring will be caught by a loop of chain if it tumbles during its fall. By Newton's Third law, when the ring twists into and hits the chain, the impact transfers momentum to the end of the chain, which rises up and over the ring- seen here in 480 fps slow motion. 

Wringing Guage Blocks

Guage block sets can be a bit pricy, but some fairly inexpensive pieces and small sets can be found for demonstrations and such:

From Amazon: BUY NOW: Gauge Blocks

Wikipedia has a nice description of Gauge Blocks and the Phenomenon of Wringing

Wringing Gauge Blocks: two blocks of metal (not magnets!) will stick together by a process called wringing if their surfaces are flat to high precision- such as these gauge blocks found in most machine shops. Here two blocks are forced apart with a snap, and then wrung back together with the characteristic sliding motion technique. Gauge blocks are flat to less that one millionth of a meter and are used by machinists for precision length measurements and calibration. The science of the wring force remains somewhat a mystery and no one has yet found a fully excepted physics description- but we do know that blocks will wring in a vacuum and that the force can be up to 30 times that of weight of the blocks. Fun physics from the shop!