{"id":502,"date":"2012-07-19T13:47:53","date_gmt":"2012-07-19T18:47:53","guid":{"rendered":"http:\/\/blog.richmond.edu\/physicsbunn\/?p=502"},"modified":"2012-07-19T13:47:53","modified_gmt":"2012-07-19T18:47:53","slug":"what-if","status":"publish","type":"post","link":"https:\/\/blog.richmond.edu\/physicsbunn\/2012\/07\/19\/what-if\/","title":{"rendered":"What if"},"content":{"rendered":"<p>No doubt anyone who&#8217;s reading this already knows about the web comic <a href=\"http:\/\/xkcd.com\/\">xkcd<\/a>. (If not, drop what you&#8217;re doing and start reading it.) But you may not know that the author, Randall Munroe, has started a <a href=\"http:\/\/what-if.xkcd.com\/\">new feature<\/a> in which he answers a weekly &#8220;what if&#8221; question about physics (broadly construed). There have been three entries so far:<\/p>\n<ul>\n<li><a href=\"http:\/\/what-if.xkcd.com\/1\/\">What would happen if you tried to hit a baseball pitched at 90% of the speed of light?<\/a><\/li>\n<li><a href=\"http:\/\/what-if.xkcd.com\/2\/\">What if everyone who took the SAT guessed on every multiple-choice question? How many perfect scores would there be?<\/a><\/li>\n<li><a href=\"http:\/\/what-if.xkcd.com\/3\/\">How much Force power can Yoda output?<\/a><\/li>\n<\/ul>\n<p>I actually don&#8217;t think his answer to the first one is quite right. He says there&#8217;d be a lot of nuclear fusion reactions, but I don&#8217;t see any reason to think there would be. The collisions are certainly energetic enough for fusion to happen, but I think the probabilities (cross sections) for other reactions, mostly simple scattering, are much higher than for fusion. At first I thought that this made a big qualitative difference in the expected behavior, but I don&#8217;t actually think it does: the ball&#8217;s kinetic energy is so large that the extra energy released via fusion wouldn&#8217;t make much difference anyway.<\/p>\n<p>Anyway, that&#8217;s a quibble. The main point is to entertain (while conveying some scientific information), and as you&#8217;d expect Munroe is awesome at that. A little excerpt:<\/p>\n<blockquote><p>Next, we need to know how fast it was rising. I went over footage of the scene and timed the X-Wing&#8217;s rate of ascent as it was emerging from the water.<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/blog.richmond.edu\/physicsbunn\/files\/2012\/07\/04.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-503\" src=\"http:\/\/blog.richmond.edu\/physicsbunn\/files\/2012\/07\/04.png\" alt=\"\" width=\"316\" height=\"200\" srcset=\"https:\/\/blog.richmond.edu\/physicsbunn\/files\/2012\/07\/04.png 316w, https:\/\/blog.richmond.edu\/physicsbunn\/files\/2012\/07\/04-300x189.png 300w\" sizes=\"auto, (max-width: 316px) 100vw, 316px\" \/><\/a><br \/>\nThe front landing strut rises out of the water in about three and a half seconds, and I estimated the strut to be 1.4 meters long (based on a scene in A New Hope where a crew member squeezes past it), which tells us the X-Wing was rising at 0.39 m\/s.<\/p>\n<p>Lastly, we need to know the strength of gravity on Dagobah. Here, I figure I\u2019m stuck, because while sci-fi fans are obsessive, it\u2019s not like there\u2019s gonna be a catalog of minor geophysical characteristics for every planet visited in Star Wars. Right?<\/p>\n<p>Nope. I\u2019ve underestimated the fandom. Wookieepeedia has just such a catalog, and informs us that the surface gravity on Dagobah is 0.9g.<\/p><\/blockquote>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>No doubt anyone who&#8217;s reading this already knows about the web comic xkcd. (If not, drop what you&#8217;re doing and start reading it.) But you may not know that the author, Randall Munroe, has started a new feature in which he answers a weekly &#8220;what if&#8221; question about physics (broadly construed). There have been three &hellip; <a href=\"https:\/\/blog.richmond.edu\/physicsbunn\/2012\/07\/19\/what-if\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">What if<\/span><\/a><\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-502","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts\/502","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/comments?post=502"}],"version-history":[{"count":0,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts\/502\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/media?parent=502"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/categories?post=502"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/tags?post=502"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}