A domino can knock over the next domino at about 1.5x larger (perhaps 2x larger) and this instant video classic from 2009 is a great example of this chain reaction. Watch University of Toronto’s Professor Stephen Morris knock over a 1-meter tall domino that weighs over 100 pounds by starting with a 5mm high by 1mm thick domino. TINY.
There are 13 dominoes in this sequence. If Professor Morris used 29 dominoes in total, with the next one always being 1.5x larger, the last domino would be the height of the Empire State Building.
After a friend tweeted about a research page full of passive motion robotics videos by Andy Ruina, Professor of Theoretical and Applied Mechanics at Cornell and of bicycle physics paper fame (SciFri video), I happened upon this 2008 video of Andy introducing his 22-pound, four-legged bi-ped robot named Ranger.
"The basic way this thing walks is that it falls down over and over again… this is walking as falling and catching yourself over and over again." In 2011, Ranger did this for 40.5 miles — that’s 307.75 laps on a running track or 65km (watch the video) — unassisted over almost 31 hours before it needed a battery recharge.
I love how not-human this bot looks. The kid should see this!