{"id":2049,"date":"2021-03-06T08:28:03","date_gmt":"2021-03-06T13:28:03","guid":{"rendered":"http:\/\/josmfs.net\/?p=2049"},"modified":"2022-10-20T12:28:21","modified_gmt":"2022-10-20T16:28:21","slug":"train-wreck-puzzle","status":"publish","type":"post","link":"https:\/\/josmfs.net\/wordpress\/2021\/03\/06\/train-wreck-puzzle\/","title":{"rendered":"Train Wreck Puzzle"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft  wp-image-2047\" src=\"https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2021\/03\/Train-Wreck-Fig2.jpg\" alt=\"\" width=\"253\" height=\"205\" srcset=\"https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2021\/03\/Train-Wreck-Fig2.jpg 503w, https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2021\/03\/Train-Wreck-Fig2-300x243.jpg 300w\" sizes=\"auto, (max-width: 253px) 100vw, 253px\" \/>I thought it might be interesting to explore the mathematics of a common problem with a store-bought HO model train set that contains a collection of straight track segments and fixed-radius curved track segments that form a simple oval.\u00a0 Invariably an initial run of the train has it careening off the track when the train first meets the curved segment after running along the straight track segments.<\/p>\n<p>Why is that?\u00a0 Well of course the train is going too fast.\u00a0 But even if it slows down enough not to fall off the curve, it still jerks unstably and may derail when it first reaches the beginning of the curve.\u00a0 What is going on?<\/p>\n<p>See the <a href=\"https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2021\/03\/Train-Wreck-Puzzle-210228.pdf\">Train Wreck Puzzle<\/a><\/p>\n<p><strong>(Updates 9\/18\/2022, 10\/20\/2022)\u00a0 Others on Circular Looping Roller Coasters <\/strong><!--more--><\/p>\n<p><strong>(Update 9\/18\/2022)\u00a0 Circular Looping Roller Coaster <\/strong><\/p>\n<p>I came across this great example of the Train Wreck Puzzle in a different setting via <a href=\"https:\/\/twistedsifter.com\/videos\/why-roller-coaster-loops-arent-actually-circular-anymore\/\">TwisterSifter<\/a>.<\/p>\n<p>\u201cWhy Roller Coaster Loops Aren\u2019t Actually Circular Anymore<\/p>\n<p>If you\u2019ve ever been on a modern looping roller coaster, you may be surprised to learn that when such \u201crailways\u201d were invented in the 1840s, they were painful, precarious, and not popular. Their biggest problem? The early loops were perfect circles.\u00a0 <a href=\"https:\/\/youtu.be\/3Kzl2suBE2w\">Watch <\/a>and see how roller coaster engineers changed the loop\u2019s design over time, trying different materials, adjusting the g-forces to exhilarating instead of nauseating, and introducing the clothoid loop.\u201d<\/p>\n<p><iframe loading=\"lazy\" title=\"Why roller coaster loops aren&#039;t circular\" width=\"625\" height=\"352\" src=\"https:\/\/www.youtube.com\/embed\/3Kzl2suBE2w?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p><strong>(Update 10\/20\/2022)\u00a0 DataGenetics Blog: Why are roller coaster loops not circular?<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft  wp-image-2918\" src=\"https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2022\/10\/Train-Wreck-DataGenetics-Rollercoaster.jpg\" alt=\"\" width=\"222\" height=\"312\" srcset=\"https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2022\/10\/Train-Wreck-DataGenetics-Rollercoaster.jpg 400w, https:\/\/josmfs.net\/wordpress\/wp-content\/uploads\/2022\/10\/Train-Wreck-DataGenetics-Rollercoaster-213x300.jpg 213w\" sizes=\"auto, (max-width: 222px) 100vw, 222px\" \/>I just came across another, more expansive, discussion of the problem with circular roller coasters, as well as purely circular curves in roads and railroad tracks, from the 2014 <a href=\"https:\/\/datagenetics.com\/blog\/march42014\/index.html\">DataGenetics Blog<\/a> by the late Nick Berry:<\/p>\n<p>\u201cMany extreme roller coaster these days have vertical loops. Have you noticed that these loops are never circular? Why is this?<\/p>\n<p>They all, also, seem to have the same similar \u2018inverted teardrop\u2019 appearance. Why is this?<\/p>\n<p>Clearly there is the same physics and mathematics involved in their designs. Let\u2019s take a look and see if we can derive a formula to describe their shape.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I thought it might be interesting to explore the mathematics of a common problem with a store-bought HO model train set that contains a collection of straight track segments and fixed-radius curved track segments that form a simple oval.\u00a0 Invariably an initial run of the train has it careening off the track when the train [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[32,217,216,12],"class_list":["post-2049","post","type-post","status-publish","format-standard","hentry","category-curiosities-and-questions","tag-calculus","tag-centrifugal-force","tag-centripetal-force","tag-curvature"],"_links":{"self":[{"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/posts\/2049","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/comments?post=2049"}],"version-history":[{"count":5,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/posts\/2049\/revisions"}],"predecessor-version":[{"id":2921,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/posts\/2049\/revisions\/2921"}],"wp:attachment":[{"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/media?parent=2049"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/categories?post=2049"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/josmfs.net\/wordpress\/wp-json\/wp\/v2\/tags?post=2049"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}