4 Revolutionary Riddles

Can you solve these four rotation-related riddles? Support Veritasium on Patreon: http://ve42.co/patreon Test yourself playlist: http://ve42.co/testurself 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 second time much faster so that the average for the two laps is twice the speed of the first lap). Someone tweeted me a video of the mystery cylinder rolling down the ramp in riddle 1 (sorry I m not sure who it was). Riddle three about a bicycle going forward or backward when it s bottom peddle is pulled back was brought to me by a number of people and I appreciate all of their help! Filmed by Raquel Nuno. Thanks to everyone at the Palais de la Decouverte! I ve had this footage for five years and am only finally releasing it now. I wanted to talk about the way grass grows on a spinning turntable but I couldn t locate the footage...