{"id":10319,"date":"2015-05-09T19:54:41","date_gmt":"2015-05-09T19:54:41","guid":{"rendered":"http:\/\/www.oracletutoring.ca\/blog\/?p=10319"},"modified":"2018-01-27T23:43:32","modified_gmt":"2018-01-27T23:43:32","slug":"physics-around-the-world-on-a-grain-of-sand","status":"publish","type":"post","link":"https:\/\/www.oracletutoring.ca\/blog\/physics-around-the-world-on-a-grain-of-sand\/","title":{"rendered":"Physics: around the world on a grain of sand?"},"content":{"rendered":"

With Einstein’s e=mc2<\/sup>, the tutor investigates an old claim.<\/h1>\n

When I was a kid, a friend of mine told me you can travel around the earth, not just once, but seven times, on the energy contained in a grain of sand. For years I’ve wondered if it’s true.<\/p>\n

Today, I’ll work the numbers for walking<\/em> around the earth seven times.<\/p>\n

Let’s assume the moderate pace of 4km\/h, ten hours per day. Let’s also assume a diet of 3000 calories per day.<\/p>\n

The circumference of the earth is 40 024km. We’ll call it 40 000km for easy figures. Let’s imagine the route isn’t direct, so is 50% longer: 60 000km.<\/p>\n

At 4km\/h, ten hours per day, our walker covers 40km per day. They’ll take 60000\/40=1500 days to circumnavigate the earth. At 3000 calories per day, they’ll consume 1500*3000=4 500 000 or 4.5e6 calories to support one round trip. Multiplying that by 7, we arrive at 31 500 000 or 3.15e7 calories.<\/p>\n

To my knowledge, the nutritionist’s calorie is 4186 J. Therefore, the walker, by consuming 3.15e7 calories, consumes 3.15e7*4186J=1.3e11J.<\/p>\n

Let’s take a look at the grain of sand. There is tremendous possible size variation from grain to grain; I imagine quite a coarse one, maybe 100 grains to a gram. Therefore, my grain of sand is 0.01g=0.00001kg=1.0e-5kg. Its energy content is<\/p>\n

e=mc^2=1.0e-5*(3.0e8)^2 =9.0e11J<\/p>\n

Let’s compare the energies:<\/p>\n

9.011e11\/1.3e11 = 6.9<\/p>\n

Apparently, the grain of sand can send the walker round the world 6.9×7\u224848 times.<\/p>\n

Coming soon: driving around the earth?<\/p>\n

HTH:)<\/p>\n

Source:<\/p>\n

Serway, Raymond A. Physics for Scientists and Engineers with Modern Physics<\/u>. \u00a0\u00a0Toronto: Saunders College Publishing, 1986.<\/p>\n

Jack of Oracle Tutoring by Jack and Diane,<\/a> Campbell River, BC.<\/p>\n","protected":false},"excerpt":{"rendered":"

With Einstein’s e=mc2, the tutor investigates an old claim. When I was a kid, a friend …<\/p>\n

Physics: around the world on a grain of sand?<\/span> Read more \u2192<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[181,7,757],"tags":[776,774,775,778,777],"class_list":["post-10319","post","type-post","status-publish","format-standard","hentry","category-lifestyle","category-physics","category-urban-myths","tag-around-the-world-on-a-grain-of-sand","tag-emc2","tag-energy","tag-relativistic-energy-content","tag-relativity"],"_links":{"self":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/10319","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/comments?post=10319"}],"version-history":[{"count":30,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/10319\/revisions"}],"predecessor-version":[{"id":28864,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/posts\/10319\/revisions\/28864"}],"wp:attachment":[{"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/media?parent=10319"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/categories?post=10319"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oracletutoring.ca\/blog\/wp-json\/wp\/v2\/tags?post=10319"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}