# The Steve Mould Effect

Simon has been dreaming to try creating the Steve Mould effect, or the chain fountain phenomenon, also known as the self-siphoning beads. It’s a counterintuitive physical phenomenon, almost a magic trick, that occurs when you place a chain of beads inside a beaker and pull on one end of the chain, allowing it to fall to the floor beneath. This establishes a self-sustaining flow of the chain of beads which rises up from the jar into an arch ascending into the air over and above the edge of the jar with a noticeable gap (the higher the distance between the floor and the beaker, the higher the arch), as if being sucked out of the jar by an invisible siphon.

According to the Wikipedia page about the chain fountain phenomenon, a ball chain (or anything with rigid links) produces the best results. Indeed, we had beautiful results with a 50m long nickel ball chain, but a 1m long pearl necklace also worked, even though the links it had weren’t that rigid (just knots of cotton thread)! Anything for science, I’m a young scientist’s mom.

Simon was delighted to learn that this phenomenon has actually been officially named after one of his favourite science presenters on YouTube, Steve Mould. Mould’s YouTube video, in which he demonstrated the phenomenon of self-siphoning beads and proposed an explanation, brought the problem to the attention of academics John Biggins and Mark Warner at Cambridge University! They published their findings in Proceedings of the Royal Society A.

So what’s the scientific explanation? According to Wikipedia, the chain fountain effect is driven by upward forces which originate inside the jar. The origin of the upward force is related to the stiffness of the chain links, and the bending restrictions of each chain joint. When a link of chain is pulled upward from the jar, it rotates like a stiff rod being picked up from one end. This rotation produces a downward force on the opposite end of the link, which in turn generates an upward reactive force. It is this upward reactive force that has been shown to drive the chain fountain phenomenon. A similar effect is observed when pouring viscous fluids from a beaker, Steve Mould pointed out.

We should warn anyone who’s about to buy ball chain, however, that it’s not only the joy of watching the chain fountains flow, but the tears of spending hours of untangling the wretched thing!

# Live Stream #6. (Mostly) Chapter 2 of Living Code: Forces.

Simon’s latest live stream on Thursday, January 11 was a blast! For the first time in his programming career he actually had quite a few viewers – largely thanks to Daniel Shiffman, who posted an announcement about Simon’s live session in his Twitter:

During the session, Simon recorded 6 tutorials:

• a bonus video about vectors,
• a video about forces in general,
• a video about the Friction Force,
• a video about Air Resistance
• and a video about Gravitational Attraction.

All as part of his “Living Code” Course. The lessons in the course are loosely based on Daniel Shiffman’s book “The Nature of Code“, but focus on JavaScript.

Simon was worried in the beginning, because he had forgotten to prepare for the stream and had no choice but do the theory (on physical forces) on the fly. It was wonderful to see how the competent viewers gave him a helping hand every now and then and generally encouraged him in the live chat. He even got a real Q&A session in the end, something he had always dreamed of:

# Simon’s Codea Tutorials and the Arc-Tangent

A set of awesome Codea tutorials that Simon recorded for those who are just starting to program in Codea. Simon ported examples from Processing (java) into Codea (Lua):

In the second tutorial (in two parts), Simon explains how to write a physics simulation program in Codea using forces like gravity, friction and spring force. Anyone watching will get to use some trigonometry and see what arc-tangent is for! The original code in Java comes from Keith Peters (Processing).

Here are some notes from when Simon was explaining the arc-tangent to me the other day:

# Simon changed an “Attraction with many movers” example from The Nature of Code

Simon’s creative “remix” of example 2.7 from Daniel Shiffman’s The Nature of Code, Chapter 2 (Forces).

# Translating examples from The Nature of Code into Lua (Codea)

This morning Simon attempted to make a more difficult translation in the Codea app of an example from Daniel Shiffman’s book The Nature of Code (Java) into Lua. It concerned the Gravitational Attraction example from Chapter 2 of the book, Forces. Simon is happy with Codea because “It’s really readable!”, “You don’t need semicolons and parenthesis!” and all logic operators are actually typed in words (“and”, “or”, “not”).

Unfortunately, the function Simon introduced as substitute for mouse pressed release on the touch screen didn’t seem to work:

Simon did successfully translate the simple harmonic motion example from Chapter 3, Oscillation: “I use trigonometry!”

For this example, he had to look up a complex formula for mapping a range to another range on the internet b1 + (s – a1)*(b2 – b1)/(a2-a1) “because map function doesn’t exist in Codea, so I wrote that function”.

Swapping the axes:

# Playing with examples on Forces and Oscillation from The Nature of Code

Playing with examples from Chapter 3 of The Nature of Code, Oscillation, covering trigonometry and connecting it to forces. The examples included simple harmonic motion, angular velocity and waves, as well as gravitational attraction from Chapter 2, Forces.

Simon also found a way to be like Daniel Shiffman – he programmed a large webcam canvas and shifted his Processing canvas to the side:

# The Nature of Code Forces example translated into Lua

Another translation involving the Codea app, only this time Simon decided to translate an example from Daniel Shiffman’s book The Nature of Code (Java) into Lua. The example comes from Chapter 2 of the book, Forces, and focuses on creating forces in the Processing world. Forces are vectors that can be applied to objects, those can be either some forces made up specifically for a project or forces modelling those already present in the real world. The chapter discusses Newton’s second law in detail (Net Force equals mass times acceleration). I have noticed that, thanks to Daniel Shiffman, Simon knows the three Netwon laws very well by now.

Simon introduced gravity, restitution, mass (many objects of varying mass) and wind to his Lua sketch:

Here is a photo of Simon’s code after he added restitution (velocity times -0.8):

In the second video, Simon also briefly talks about the force of friction (Frictio=µNv). He read about friction in the same chapter and became fascinated with it. Since he was telling me about it when we were outside today, I asked him to repeat it in the video.

# Life as a Battle of Forces

Simon loves it when we read Larry Gonick’s Cartoon Guide to Physics (we have a Russian translation). My guess is that book is partially responsible for him trying to picture his daily experiences in vectors. Or maybe it’s just Simon. This is today’s scoop:

After going to the playground where he climbed the slope pulling himself up holding on a rope and jumping off it, wondering which forces affect him

Taking a bath and thinking about how bubbles appear after you throw something heavy in the water

Reflecting on why cylinders roll in a straight line and cones roll in circles