{"id":122643,"date":"2015-09-08T02:00:00","date_gmt":"2015-09-07T23:00:00","guid":{"rendered":"http:\/\/www.fyysika.ee\/?guid=40bfc84e976346f55ffaa14125557036"},"modified":"2015-09-08T02:00:00","modified_gmt":"2015-09-07T23:00:00","slug":"simple-measurements-of-rolling-friction-and-deformation-when-r-0-001","status":"publish","type":"post","link":"https:\/\/www.fyysika.ee\/?p=122643","title":{"rendered":"Simple measurements of rolling friction and deformation when &mu; r &lt; 0.001"},"content":{"rendered":"<p>A simple method is described to measure the coefficient of rolling friction, ##IMG##<br \/>\n[http:\/\/ej.iop.org\/images\/0143-0807\/36\/6\/065018\/ejp519061ieqn3.gif] {${mu }_{{rm{r}}}$} , for a<br \/>\nhard ball rolling on a hard, horizontal surface. The method involves attaching a small mass to the<br \/>\nside of the ball so that the ball precesses slowly along a spiral path. Since the radius of<br \/>\ncurvature decreases slowly with time, the decrease in ball speed can be measured over a relatively<br \/>\nlong path length on a small area surface. Results are presented for three steel bearing balls and a<br \/>\nbilliard ball rolling on a polished granite surface, with ##IMG##<br \/>\n[http:\/\/ej.iop.org\/images\/0143-0807\/36\/6\/065018\/ejp519061ieqn4.gif] {${mu }_{{rm{r}}}$} ranging<br \/>\nfrom 0.000 086 to 0.000 84. Estimates of the combined deformation of the ball and the surface are<br \/>\nalso presented, based on impact duration measurements at very low impact forces.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A simple method is described to measure the coefficient of rolling friction, ##IMG##<br \/>\n[http:\/\/ej.iop.org\/images\/0143-0807\/36\/6\/065018\/ejp519061ieqn3.gif] {${mu }_{{rm{r}}}$} , for a<br \/>\nhard ball rolling on a hard, horizontal surface. The method involve&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[178],"tags":[],"class_list":{"0":"post-122643","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-rss-fuusikaharidus","7":"entry"},"_links":{"self":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/122643","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=122643"}],"version-history":[{"count":0,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/122643\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=122643"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=122643"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=122643"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}