Physics lesson for a teacher of physics, history and anthropology.

Prototype, know-how, business idea, scientific experiment, life hack, starter, handmade, science, physics, light industry, mass product, sports, style, recreation, extreme recreation, military equipment, sports equipment, protection, comfort..
Download and read in the public domain: https://drive.google.com/drive/folders/1Mlz4cCuzs_9rh_cbn0C4jB9UbOQ11-aq?usp=sharing
and
https://independent.academia.edu/YaroslavZaitsev