Sep 30, 2026 · 41 min
A kendama turns catching into a lesson in physics
Hacking The Kendama With Physics
The episode shows how a simple skill toy exposes the mechanics of balance, prediction, materials, and learning before extending those ideas to swimming and planetary science.
- 1Kendama tricks depend on pendulums, angular momentum, gyroscopic stability, and matching the ball’s velocity.
- 2A heavier, redesigned kendama changes stability and control, showing how materials and geometry shape performance.
- 3Listener questions connect mathematical thinking to faster swimming, Jupiter’s extreme interior, and relearning calculus and statistics.
Don't miss
The comparison between the ordinary kendama and Adam Savage’s heavier, centered-string design makes gyroscopic stability and material choice tangible.
The brief
Michael Stevens and Hannah Fry begin with the kendama, a Japanese cup-and-ball toy whose deceptively simple spike challenge reveals how much physics catching requires.
The hosts compare the original toy with Adam Savage’s heavier custom kendama, using its centered string attachment, Delrin construction, and gyroscopic stability to explain why design changes control.
The kendama becomes a bridge to robotics: learning to predict a toy’s motion resembles teaching machines about their limbs, surroundings, and the consequences of action.
Listener questions widen the frame, covering mathematical ways to swim faster and why neither a person nor a spacecraft could simply fly through Jupiter.
The episode closes with practical guidance for adults returning to mathematics, favoring books that build calculus and statistics gradually through concepts and human-centered examples.
Featuring
Hannah Mary Fry
Adam Savage
kendamaBooks & mentions
Stewart Calculus
A structured textbook option for rebuilding calculus from foundational concepts.
Spivak Calculus
A more conceptual route into calculus for readers ready to return to mathematical ideas.
Hello World
Hannah Fry’s accessible exploration of how algorithms and artificial intelligence shape human life.
Listen to the full episode and explore every guest, topic, and moment on PodLume.