### Coin Escape Puzzle

Available here:

From eBay: **Search NOW: Coin Escape Puzzle**

From Grand Illusions:** BUY NOW: Coin Escape Puzzle**

Another coin escape puzzle (fits US Dollar), the YOT:

From Amazon: **BUY NOW **

Silver Dollar Escape Puzzle

Coin Escape Puzzle: physics brain teaser- remove the coin without breaking the container or using any tools other than your hands. Of course you spin it to get the quarter out- but exactly how? The solution to this puzzle (like others featured here) relies on some fun basic physics of spinning things. Answer below and swipe to reveal solution.

### Raketti Puzzle

Versions of this puzzle avaioable fron these sources:

From CuriosityBox: **BUY NOW Raketti Physics Brain Teaser**

From Etsy: **BUY NOW Raketti Physics Puzzle **

Raketti Puzzle: a favorite physics brain teaser in my collection- the challenge is to remove the cone topped cylinder from the hole without touching the bottom container (no fair using sticky tape). It can be done in a matter of seconds! The solution to this puzzle (like others featured here) relies on some fun physics principles.

### Two Marble Puzzle

Great versions of the puzzle avaliable:

From Amazon:** BUY NOW: Two Marble Puzzle, **or get this** set of puzzles**

From Etsy:** BUY NOW: Two Marble Puzzles**

Similar 4 marble version of this puzzle available here:

From Etsy: **BUY NOW Four Marble Puzzle **

Two Marble Puzzle: physics brain teaser- move both marbles to their top locations on each side simultaneously. The solution to this puzzle relies on some fun basic physics principles- can you figure out which ones? Swipe to reveal solution. Found this well made version of this classic physics puzzle at a gift shop in San Francisco (note Golden Gate Bridge motif).

### Poly Density Puzzle

Get the kit here:

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?

### Flippe Puzzle Ball

Get this puzzle ball here:

From Etsy:** BUY NOW: Flippe Puzzle Ball**

Flippe Ball Puzzle: this ball is a puzzle that explodes and flies apart when spun. The puzzle is made of three identical pieces and a ball bearing which mysteriously locks the pieces together only to release them after a period of spinning. The main challenge is to fully explain why this spontaneous disassembly occurs. Swipe to see a slow motion boomerang loop of it coming apart- and how conservation of momentum has the three equal mass pieces on equally spaced trajectories (120°) with the ball bearing remaining stationary at the center. A product of puzzle master George Bell.

### Repelling Marbles Puzzle

Get this affordable and fun kit here:

From Educational Innovations:** BUY NOW Mystery Marbles Puzzle Kit **

Mystery Marbles Puzzle: a physics brain teaser (now available as a kit) what's going on here? Three glass marbles can move but stay separated in this liquid filled tube no matter the orientation- why do they not touch? Swipe for reveal of components.

**See also: Poly-acrylamide Polymer Vanishing Act**

### Four Marble Puzzle

Get this well crafted puzzle from Creative Crafthouse here:

From Amazon: **BUY NOW Crossroads Four Marble Puzzle **

From Etsy: **BUY NOW Four Marble Puzzle **

Four Marble Puzzle: physics brain teaser- move all four marbles to their corner locations simultaneously. Each slot slopes down towards the center such that the marbles tend to stay at the center- so, how would one get them to roll outward at the same time? The solution to this puzzle (like others featured here) relies on some fun basic physics principles. Answer below and swipe to reveal solution. A beautiful and well-made puzzle from Creative Crafthouse.

### Pentominoes 3 Color Challenge

@physicsfun exclusive design- available only from **STEMCell Science**:

From Etsy: **BUY NOW: 3 Color Pentominoes Puzzle**

Pentominoes 3 Color Challenge: fit all 12 pentominoes into a 6x10 rectangle such that no two identically colored pieces touch. Pentominoes are the set of all 12 possible arrangements of five identical squares joined edge to edge. Since 5x12=60, the pentominoes can tile a 6 x 10 rectangle with no gaps (there are 2339 ways to do this- yet even finding one solution is quite difficult). Adding the 3 color challenge reduces the number of possible solutions to just this one shown here! Made from laser cut acrylic and wood- and now available for the first time in a limited production run.

### TrueBalance

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!

### Magnetic Soma Cube

Get this inexpensive SomaCube here:

From Amazon: **BUY NOW: Magnetic Soma Cube**

Magnetic Soma Cube: a new fun variant of the famous math toy invented by Danish scientist and artist Piet Hein, who claimed that this puzzle came to him as he was listening to a lecture on Quantum Mechanics by Werner Heisenberg (yes- that Heisenberg). The seven pieces of this puzzle are all the ways 3 or 4 cubes can be joined such that the piece has at least one inside corner. In this version small magnets are encased in cleverly designed cavities such that they will always flip over to attract a counterpart in another puzzle piece, allowing the puzzle to stick together- or hang from the side of the refrigerator. Amazingly there are 240 ways to make the cube from these 7 pieces- still not that easy!

### Pearl Vault Puzzle

Get this puzzle here:

From Etsy: **BUY NOW: Pearl Vault Puzzle**

Pearl Vault Puzzle: a tetrahedron assembly of four identical pieces traps within a pearl. Three challenge aspects to this puzzle: 1) get the pearl out from the center, 2) explain the physics of how the disassembly occurs, and 3) reassemble- for which 3) might be the most challenging. Swipe for reveal and note the conservation of momentum aspect of the solution. Designed by Bruce Patterson and expertly produced by Pyrigan Puzzles.

### Aristotle's Wheel Paradox

Get this demonstration puzzle here:

From Etsy: **BUY NOW: Aristotle's Wheel**

WIkipedia has some details on the Wheel "Paradox"

Aristotle’s Wheel “Paradox”: How does the smaller attached disk travel the same length as the larger one if both disks only make one full rotation? Note the shorter path of the smaller disk, if rolled on its own. This beautifully made demonstration depicts an issue of geometry and motion that perplexed the best minds of humanity for 2000 years. The ancients knew the formula for circumference, and C=2πR for the large disk is clearly greater than C=2πr for the smaller- so how could the smaller disk, rotated once, still travel the distance of the larger one if attached? The great Galileo even offered a solution to the problem in his book Two New Sciences, where he approximated the situation as concentric hexagons and considered the limit as the number of sides increased. So what is the best answer to make sense of this situation?

### 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.

### Matsuyama's Paradox

Get this and other amazing math puzzles here:

From Etsy: **BUY NOW: Missing Square Puzzle**

Matsuyama’s Paradox: dissect a large square in to four equal quadrilaterals, rotate and reassemble- to find a small square is missing! Where did the additional area come from? Fun math involved in the design of this puzzle, which illustrates how the concept of area can often challenge our intuitions. Swipe to compare the two assemblies. A precision crafted puzzle by Jeux Efcé game shop. Wikipedia has good details: Missing square puzzle.

### Stomachion Puzzle

Get this 3-color laser cut acrylic version here:

From Kadon Enterprises: **BUY NOW: Stomachion Puzzle**

Also a very nice multicolor acyrlic version here:

From Etsy: **BUY NOW: Stomachion Puzzle**

Learn about the 1998 discovery of the lost writings of Archimedes (and the technology used to recover them) in this TED talk.

Ancient Stomachion Puzzle: the oldest known puzzle, discovered in the writings of the great Greek physicist and mathematician Archimedes from some 2200 years ago. The puzzle is a dissection of a square into 14 polygons, where the areas of each piece are integer multiples of each other (a curious way to slice it up). In 2003 Bill Cutler showed that there are 536 district ways to configure these pieces to make the square (five are shown here), ignoring simple rotations and reflections. Swipe to see the most famous solution, attributed to Archimedes himself, that was found in an ancient manuscript discovered only in 1998- before this date historians knew the name of the puzzle, but no one knew what it looked like. Kate Jones, the maker of this particularly aesthetic version, found that when using only three colors for the polygons, there are only 6 solutions where no two pieces of the same color touch (four solutions shown here).

### Nova Plexus Interlocking Puzzle

Precision machined and available in brass or stainless steel:

From Art of Play: **BUY NOW: Nova Plexus Puzzle**

Nova Plexus Puzzle: 12 identical brass rods can create 4 interlocking triangles in a perfect symmetry- look carefully and you can see that each rod is in an identical configuration with the 5 others that connect with it. Precision machined notches on the ends of the rods allow them to interlock with elastic tension such that vector sum of the 5 forces on each rod is zero- creating this astonishing geometry as the equilibrium state. Unlock the ends of any two rods and the system instantly disassembles (swipe to view process in slow motion). Invented/designed by artist and computer scientist Geoff Wyvill in 1978, this puzzle has just recently been made available for sale with a limited production run.

### Soma Cube

The Soma Cube is available in a variety of materials and colors:

From Amazon: **BUY NOW: Soma Cube**

From Etsy: **BUY NOW: Soma Cube**

Soma Cube: Math toy invented by Danish scientist and artist Piet Hein, who claimed that this puzzle idea came to him as he was listening to a lecture on Quantum Mechanics by Werner Heisenberg (yes- that Heisenberg) in 1933. The seven pieces are all the ways 3 or 4 cubes can be joined, such that each piece has at least one inside corner. Amazingly there are 240 ways to make the larger cube from these 7 pieces- still not that easy!

### Frabjous Geometric Sculpture Puzzle

Get one here- five colors to choose from:

From MoMath: BUY NOW: Frabjous Sculpture Puzzle

Frabjous Geometric Sculpture Puzzle: 30 identical laser cut acrylic pieces interlock into 12 interconnected five point stars (each with a spiral vortex center) in this puzzle based of the Frabjous sculpture by artist and professor of mathematics George Hart (Prof. Hart is now on Instagram, follow him at @george.hart.sculptor to see more of his amazing work.) Note that if one connects the tips of the stars one gets the outline of a dodecahedron, with its 30 edges and 12 sides, and if one considers the face planes of the linked pentagrams the underlying shape is a polyhedron called the “great rhombic triacontahedron”. A year or so ago I got to visit the National Museum of Mathematics in NYC where I bought this puzzle in the @momath1 museum shop. This puzzle was great fun to assemble- buy one to support this inspirational museum, and make a great sculpture for your bookshelf!