A real victory for Simon, who has had a bit of a fear of heights for years. But what he found most impressive were the noticeable changes in gravity while going up and down with the elevator. When descending from the 72nd floor he could feel the decreased G!
Here Simon explains one more effect he has played with at home, the Magnus effect.
Inspired by the Veritasium channel, Simon tests throwing a Slinky nd watching it collapse together and only then fall to the ground. He then ties a tennis ball to the Slinky and observes how it would behave if he throws it out of the window.
We drew a line to mark how far the sea has pulled back between 17:30 and 21:00 o’clock. It’s amazing to observe the the Moon in action! We have read about this dance that the Earth and the Moon dance with each other, circling round and round in what is currently our favorite book, Eine kleine Nachtphysik by Wolfgang Rosler:
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:
This is a beautiful “lecture” that Simon in his pajamas, chocolate paste adorning is face, game me Friday morning. He spoke about pendulum force, a force he was about to apply in a coding project.
The other videos form the very beginning of the lecture, with Simon plays with sine and cosine and explains why location, velocity and acceleration can be vectors and can be angles:
And this is the code where pendulum force is used. It’s an example from The Nature of Code book by Daniel Shiffman, from Chapter 3 on Oscillation:
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 (Friction =−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.
In this project Simon combined two exercises and one example from Daniel Shiffman’s Nature of Code book, Chapter 5 – Physic Libraries. The specific physics library used here is Box2D. Simon combined exercises 5.6 (Bridge) and 5.10 (Attraction Apply Force), and example 5.7 (Create a windmill) to create a motor that catapults particles towards an attractor. If the particles fly past the attractor, “bricks” can be added to the canvas by clicking the mouse – the weight of the bricks helps regulate the motor in the right direction. For this project, both gravitational attraction and global gravity force were applied: