Hacking The Kendama With Physics
Summary
Michael Stevens and Hannah Fry explore the physics of the Japanese skill toy kendama, comparing a traditional wooden version with a custom Delrin model built by Adam Savage to utilize gyroscopic stability. They discuss how the heavy, machined ball makes the trick easier to master and draw parallels to DeepMind’s robots learning cup and ball through trial and error. The episode also covers viewer questions on the mathematics of efficient swimming strokes, the internal structure of Jupiter’s fuzzy core, and recommended textbooks for adults returning to math and statistics.
Topics discussed
Introduction and the Kendama gift
Michael's history with the game
Sponsors: Cancer Research UK and Carvana
Sponsor: Apple Watch Series 12
Attempting the basic spike trick
Introducing Adam Savage's custom Kendama
Physics of the custom design: Torque and weight
Gyroscopic stability and successful spike
Machining details of the Delrin Kendama
Attempting cup tricks and friction issues
Robots learning physics via Cup and Ball
Comparison with paper yo-yos and child play
Brain predictions and the joy of discovery
Reflections on the editing and material changes
Deep dive into gyroscopic precession
Gyroscope behavior on ships and in gimbals
Break and Apple Watch ad
Q&A: Math and fluid dynamics in swimming
Q&A: The aquatic ape theory and swim suits
Q&A: The interior of Jupiter and the Juno probe
Q&A: Recommended math and stats textbooks
Hannah's book recommendation: Hello World
Outro and call to action
Promo for Rest is History: Reign of Terror
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