Chao-c'<p>This is not exactly new, but still, each time I think about downwind carts, by heads explodes again. It is not perpetual motion machine, but it looks like one! It just shows, that our intuitive understating how closed systems can extract energy from environment is oversimplified.</p><p>When thinking about how it is possible, it is probably somehow related to the fact, that ice skate sails can travel much faster, than conventional sail ships (sail foils can do better, but not as good as ice sails). And this can be combined with the fact, that cruising sail ship can actually outrun boat sailing just straight downwind. But this still doesn't help you to understand, how downwind cart works, except the fact the propeller also somehow "cruises", not in a straight line...</p><p><a href="https://www.youtube.com/watch?v=jyQwgBAaBag" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="">youtube.com/watch?v=jyQwgBAaBag</span><span class="invisible"></span></a></p><p><a href="https://f.cz/tags/downwindcart" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>downwindcart</span></a> <a href="https://f.cz/tags/physics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>physics</span></a> <a href="https://f.cz/tags/fringe" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>fringe</span></a> <a href="https://f.cz/tags/mechanics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mechanics</span></a> <a href="https://f.cz/tags/wind" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>wind</span></a> <a href="https://f.cz/tags/energy" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>energy</span></a></p>