Physics experiment at home: measure oscillations of a pendulum with computer vision

I have been experimenting with Computer Vision lately. In my previous posts (this one and this one) I measured bridge vibrations with a camera from a distance. This time I decided to go back to the basics and apply this technique to measure the oscillations of a pendulum.

Knowing that the period of vibrations of a pendulum depends on its length, I filmed three different pendulums with different lengths. Theoretically, for small angles, the period of the pendulum is:

where L is the length of the pendulum and g is acceleration of gravity. Without air resistance, the pendulum would oscillate forever, but in reality the oscillations are gradually damped.

I mounted the camera on a tripod and I secured the pendulum with my hand. Since I can't keep my hand perfectly steady, I tracked both the movement of my hand and the movement of the mass and I calculated the horizontal component of the displacement of the pendulum relative to my hand.

So here is the result:

I basically used the same Python code I used in my previous posts to track vibrations of bridges. If you are interested to learn how to write the code and use it yourself, please read my post.

Merry Christmas and a Happy New Year 2021!