As I get further into using Kangaroo as a powerful tool to guide my interest in kinetic art, I’m feeling increasing aware of the many holes in my understanding of how it works. @DanielPiker did a great job explaining here, and I’ve looked at prior pendulum examples - but after doing some very basic experiments, I can’t explain the results.
First, I set up two simple pendulums (point mass at bottom, massless string - “plumb bobs”). I set one to twice the length of the other, and compared their respective periods:
Since the equation describing the period of an idealized simple pendulum is T = 2Pi*sqrt(length / g-force), doubling the length should increase the period by sqrt(2), which is what I found (given more time, the number of 1-length cycles divided by 2-length cycles converges nicely to 1.414).
pendulum length.gh (22.9 KB)
Second, instead of doubling the length, I doubled the mass of the second pendulum (or at least I thought I did), by adding a second point very close to the “bob”. I expected the added mass to cause no (or very little) change to the period, but:
pendulum mass.gh (24.0 KB)
Clearly, I’m missing something - l’il help, please.