4 Revolutionary Riddles

Can you solve these four rotation-related riddles? Support Veritasium on Patreon: Test yourself playlist: Huge thanks to Patreon supporters: Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen I came across these four physics puzzles over the years in discussions with Neil deGrasse Tyson (riddle 4: which part(s) of a moving train are going backwards with respect to the ground?), Simon Pampena (riddle 2: run around a track twice, the first time slowly, the