How to measure flexibility of an object using just video?

What tutorials can aid with this?

Answer 1

[Stephen Jue]

One measure of the flexibility of an object is stiffness , which is applied force divided by displacement of the object:

Assuming the video is high enough resolution to detect these small displacements in the object, you could use object tracking to measure the displacement. Then you can calculate the stiffness of the object by dividing the applied force by this displacement.