{"id":256,"date":"2020-04-14T22:34:23","date_gmt":"2020-04-14T22:34:23","guid":{"rendered":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/?page_id=256"},"modified":"2026-05-13T07:19:11","modified_gmt":"2026-05-13T07:19:11","slug":"rotatingplatform","status":"publish","type":"page","link":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/exhibits\/mechanics\/rotatingplatform\/","title":{"rendered":"Rotating Platform and Dumbbells"},"content":{"rendered":"<h1 style=\"margin-top:var(--wp--preset--spacing--50);margin-bottom:var(--wp--preset--spacing--20)\" class=\"is-style-mini-bar wp-block-post-title\">Rotating Platform and Dumbbells<\/h1>\n\n\n<div class=\"wp-block-group alignfull has-base-background-color has-background has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:0;margin-bottom:0;padding-top:var(--wp--preset--spacing--40);padding-bottom:var(--wp--preset--spacing--60)\">\n<div class=\"wp-block-columns alignnone is-layout-flex wp-container-core-columns-is-layout-b4b75a54 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-layout-constrained has-global-padding wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-b4b75a54 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"171\" height=\"300\" src=\"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-01.jpg\" alt=\"\" class=\"wp-image-257\"\/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-1A-1024x768.jpg\" alt=\"\" class=\"wp-image-175\" srcset=\"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-1A-1024x768.jpg 1024w, https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-1A-300x225.jpg 300w, https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-1A-768x576.jpg 768w, https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/RotatingPlatform-1A-1200x900.jpg 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">WHAT TO DO:<\/h2>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-b4b75a54 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<ol class=\"wp-block-list is-style-more-space\">\n<li>STAND ON THE TURNTABLE WITH A DUMB-BELL IN<span style=\"font-size: 0.9em;\">\u00a0EACH HAND.<\/span><\/li>\n\n\n\n<li>STRETCH YOUR ARMS STRAIGHT OUT AT YOUR SIDES.<\/li>\n\n\n\n<li>HAVE A FRIEND START YOU ROTATING <strong>SLOWLY.<\/strong><\/li>\n<\/ol>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image alignright is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"155\" height=\"145\" src=\"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/Dumbbell1.gif\" alt=\"\" class=\"wp-image-258\" style=\"width:218px;height:auto\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-b4b75a54 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"153\" height=\"129\" src=\"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-content\/uploads\/sites\/10\/2020\/04\/Dumbbell2.gif\" alt=\"\" class=\"wp-image-259\" style=\"aspect-ratio:1.1861119799812323;width:218px;height:auto\"\/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong><u>WHAT HAPPENS WHEN YOU PULL THE DUMB-BELLS IN TO YOUR SIDES?<\/u><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><u>WHAT HAPPENS WHEN YOU STRAIGHTEN YOUR ARMS AGAIN?<\/u><\/strong><\/p>\n<\/div>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><u>ANSWER<\/u><\/strong>:&nbsp; When you pull your arms in, you speed up.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When you straighten your arms back out, you slow down again.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">WHY DOES THIS HAPPEN?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Cautions, Warnings, or Safety Concerns:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list is-style-more-space\">\n<li>The volunteer may get dizzy from spinning.<\/li>\n\n\n\n<li>The volunteer should be careful in getting on\/off the rotating platform.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Discussion:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Once the volunteer is spinning, he or she has some amount of angular momentum, L, which must be conserved. This is given by L = I*\u03c9. When the volunteer brings his or her arms into the center, the moment of inertia I is decreased. Since L is constant, \u03c9 must increase, which is what we observe.<\/p>\n\n\n<div style=\"font-size: 1.125rem\" class=\"is-style-blockquote wp-block-uw-blocks-uw-quote\">\n\t<blockquote><em>Original 1918 Museum Exhibit<\/em><\/blockquote>\n\t<div class=\"uw-quote-bottom-container\">\n\t\t\t<\/div>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><i><b><a href=\"https:\/\/wiki.physics.wisc.edu\/facultywiki\/Demonstrations\">Physics Lecture Demonstration Database<\/a><\/b><\/i><\/p>\n\n\n\n<ul class=\"wp-block-list is-style-more-space\">\n<li><a href=\"https:\/\/wiki.physics.wisc.edu\/facultywiki\/Rotating_Platform\">Rotating Platform and Dumbbells, 1Q40.10<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>WHAT TO DO: WHAT HAPPENS WHEN YOU PULL THE DUMB-BELLS IN TO YOUR SIDES? WHAT HAPPENS WHEN YOU STRAIGHTEN YOUR ARMS AGAIN? ANSWER:&nbsp; When you pull your arms in, you speed up. When you straighten your arms back out, you slow down again. &nbsp; WHY DOES THIS HAPPEN? &nbsp; Cautions, Warnings, or Safety Concerns: Discussion: &hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":50,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_uw_migration_status":"complete","_uw_gutenberg_post_content_before_migration":"","_uw_seo_meta_title":"","_uw_seo_meta_description":"","_uw_seo_twitter_card_type":"","_uw_seo_meta_image":"","_uw_seo_meta_image_url":"","_uw_seo_meta_image_sizes":[],"_uw_seo_custom_meta_tags":[],"footnotes":""},"class_list":["post-256","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/pages\/256","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/comments?post=256"}],"version-history":[{"count":8,"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/pages\/256\/revisions"}],"predecessor-version":[{"id":1006,"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/pages\/256\/revisions\/1006"}],"up":[{"embeddable":true,"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/pages\/50"}],"wp:attachment":[{"href":"https:\/\/wp.physics.wisc.edu\/ingersollmuseum\/wp-json\/wp\/v2\/media?parent=256"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}