tag:blogger.com,1999:blog-9453241.post110531209959615950..comments2024-01-22T23:57:51.851-07:00Comments on Phase Portrait: Tsunamis and Polar IceTed Pavlichttp://www.blogger.com/profile/15297790411942050417noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-9453241.post-82624251224163905112009-04-09T16:16:00.000-07:002009-04-09T16:16:00.000-07:00The analogy comparing the spinning skater to the e...The analogy comparing the spinning skater to the earth didn't really involve gravity in any consequential way. That is, in the example given in the post, the ice skater's "arms" play the same role as the gravity of the earth. Gravity holds the "bowling ball" close to the body. After that, the dynamics are the same. If gravity is able to pull mass closer to its center, a spinning object will have a "more stable" rotation. Likewise, the closer the skater can hold the "bowling ball" to her body, the more stable her rotation.<BR/><BR/>The important thing is the spinning -- not the gravity. The effects come from angular momentum (and its conservation); they are not anything special related to gravity.<BR/><BR/>THAT BEING SAID, certainly the geometry of the earth changes the "amount" of gravity. It's as if the position of the skater's bowling ball actually changed the "stretchiness" of her arms. However, the earth's diameter is very large, and we're talking about *relatively* small changes in the shape of a SMALL part of the earth (it's surface). Those small changes should not change the gravity holding the planet together. They just might change how it spins (i.e., speed and "stability").<BR/><BR/>I hope that answers your question.Ted Pavlichttps://www.blogger.com/profile/15297790411942050417noreply@blogger.comtag:blogger.com,1999:blog-9453241.post-40719546774923490382009-04-09T15:42:00.000-07:002009-04-09T15:42:00.000-07:00Wow! Very interesting read. I'm fascinated by ts...Wow! Very interesting read. I'm fascinated by tsunamis and earthquakes. Mostly because I love living in the littoral regions... Question comparing the spin of the ice skater to the spin of the earth. Is gravity in terms of the ice skater on earth different than gravity in terms of the earth in the solar system? I really don't know!Anonymousnoreply@blogger.com