5-axis

Veritasium explains the Dzhanibekov effect, also called the tennis racket theorem, where a spinning object flips unexpectedly about its intermediate axis. The video gives an intuitive account of the underlying rotational dynamics, drawing on Terry Tao's explanation and the original papers.

Numberphile's Ben Sparks shows why the golden ratio is the most irrational number, using seeds, continued fractions and rational approximations. He also explains why plants use it for spacing leaves and seeds.

CGP Grey explains how traffic jams come from human driving behavior such as tailgating and reaction delays, and how leaving gaps and smoothing speed would reduce congestion. It also touches on self-driving cars.

FortNine looks at why Tesla Autopilot has rear-ended motorcyclists, speculating that the vision system misreads motorcycle taillights as a distant car. It argues that radar and other sensors would help.