Ukaia

Ukaia / studies in motion

Motion, explained with care.

Ukaia is a small studio for people who want to understand how mechanical things move. We write short studies, longer guides and a few instruments that run in the browser. Simple rules can still produce motion that is hard to predict, and most of our work is about that gap.

The instrument: a double pendulum

Your browser cannot draw the live instrument. The static drawing and the guide describe the same motion.
The pivot sits at the centre. Each angle is measured from straight down, so zero hangs still and 180 degrees is balanced upright. Both arms have equal length and both bobs have equal mass.

The live instrument needs JavaScript. The drawing above shows the starting position. The guide explains the motion in words and in a diagram.

Starting conditions
120°
-10°

Angles apply when you press Reset. Degrees are measured from straight down.

Elapsed time
0.0 s
Gap between tips
Twin off

Four studies

Studies

Short studies on pendulum period, energy, phase portraits and sensitivity to starting conditions. Each one ends with a question to answer on paper.

Long read

Guide

How to read a chaotic system without fooling yourself: what the arms do, why small differences grow, and where prediction stops.

The studio

About Ukaia

Who writes Ukaia, who it is written for, how a study is checked before it goes up, and the things we decline to do.

Write to us

Contact

Send a specific question, a correction or a request for a study. The contact page lists what makes a message easy to answer.