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RECENT POSTS IN THIS TOPIC

**Ian Harris**: *on* 9/27/14 at 2:48am UTC, wrote Very interesting concept to do a video on - I really enjoyed it! If you...

**Douglas Singleton**: *on* 9/10/14 at 19:18pm UTC, wrote Hi Teresa, We will have a look and send any comments. BEst wishes, ...

**Douglas Singleton**: *on* 9/10/14 at 19:17pm UTC, wrote Hi David, Thanks for your comments and we will certainly have a look and...

**Kristen Hamilton**: *on* 9/8/14 at 20:47pm UTC, wrote This is a very interesting video; it's a topic I had seen before, but had...

**James Walsh**: *on* 9/8/14 at 11:27am UTC, wrote Hi, About a rules change, I meant that the current rules aren't going to...

**Douglas Singleton**: *on* 9/7/14 at 19:15pm UTC, wrote Hi Marc, Thanks for viewing our video and your comments. yes the tennis...

**Douglas Singleton**: *on* 9/7/14 at 18:56pm UTC, wrote Hi James, Thanks for your comments and we will definitely have a look at...

**Marc Séguin**: *on* 9/7/14 at 2:51am UTC, wrote Mike, Max, Dan, Simon and Doug, Very interesting video! I didn't know...

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FQXi FORUM

September 21, 2021

CATEGORY:
Show Me the Physics! Video Contest (2014)
[back]

TOPIC: Moment of Inertia, Tumbling Tennis Rackets, and Rotating Rockets by Mike Blackston [refresh]

TOPIC: Moment of Inertia, Tumbling Tennis Rackets, and Rotating Rockets by Mike Blackston [refresh]

http://youtu.be/3bqq_ENKqU4

This video discusses moment of inertia, the tennis racket theorem and why the US's first artificial satellite, the Explorer 1, unexpectedly started to tumble after being placed in orbit. The video combines animation, live action experiments, and a little bit of straight whiteboard lecturing to discuss the three related topics. The video progresses from simple (moment of inertia) to progressively more complex -- the tennis racket theorem and finally the Explorer 1's unexpected tumbling. We are especially proud of the "box cam" in the tennis racket theorem segment.

Max Bright, California State University, Fresno

Dan Chase, Heald College/TDP Podcast

Simon Gonzalez, California State University, Fresno

Doug Singleton, California State University, Fresno/TDP Podcast

Mike, Dan and Doug have been teaching physics for 15+ years. They also form the nucleus of the TDP podcast which discusses physics/science over beers in once per week. Max and Simon are both physics graduate students at CSU Fresno working on particle physics research (Max) and astrophysics research (Simon). Max is a contributor to the TDP podcast and Simon has done research on the ATLAS experiment at the LHC.

Dear Messrs Blackston, Chase and Singleton,

I quite enjoyed watching your video and I do hope that it does well in the competition. I do have one small quibble about its content.

As I have shown in my video JOE FISHER’S THEOREM OF INERT LIGHT THE MUSICAL, Newton was wrong about his abstract so-called “laws of motion,” and Einstein was wrong about his abstract so-called “speed of fabricated light through a fabricated vacuum”

All surfaces travel at the same constant speed. Each sub-surface travels at a unique speed that is always lower than the constant speed of surface. The surface of an atom can only travel at the same constant speed as the surface of a star. The sub-surface of an atom will travel at a unique speed that is less than the constant speed of surface. This is why each atom is always in a unique position. The sub-surface of a star will always travel at a unique speed that will always be less than the constant speed of surface. This is why each star is unique as to its appearance and remains at a unique distance apart from all other stars and atoms.

Obviously, the satellite’s unique spin while in flight shown in your video was entirely due to the fabricated alterations made to its sub-surface.

Joe Fisher

I quite enjoyed watching your video and I do hope that it does well in the competition. I do have one small quibble about its content.

As I have shown in my video JOE FISHER’S THEOREM OF INERT LIGHT THE MUSICAL, Newton was wrong about his abstract so-called “laws of motion,” and Einstein was wrong about his abstract so-called “speed of fabricated light through a fabricated vacuum”

All surfaces travel at the same constant speed. Each sub-surface travels at a unique speed that is always lower than the constant speed of surface. The surface of an atom can only travel at the same constant speed as the surface of a star. The sub-surface of an atom will travel at a unique speed that is less than the constant speed of surface. This is why each atom is always in a unique position. The sub-surface of a star will always travel at a unique speed that will always be less than the constant speed of surface. This is why each star is unique as to its appearance and remains at a unique distance apart from all other stars and atoms.

Obviously, the satellite’s unique spin while in flight shown in your video was entirely due to the fabricated alterations made to its sub-surface.

Joe Fisher

Hi Mike, Max, Dan, Simon and Doug,

Your video was nicely done and should be successful in helping develop concepts for kids at high school age. Also, good music.

I did not realize that the satellite eventually got to spinning improperly and that the rotational energy was all still there but around other axes. Nicely explained!

I have a response to your note at my video (Special Relativity ...) comments location.

Good luck for the contest,

Alex

Your video was nicely done and should be successful in helping develop concepts for kids at high school age. Also, good music.

I did not realize that the satellite eventually got to spinning improperly and that the rotational energy was all still there but around other axes. Nicely explained!

I have a response to your note at my video (Special Relativity ...) comments location.

Good luck for the contest,

Alex

Hi Alex,

Thanks for viewing and commenting on our video. The Explorer 1 is an interesting example of rotational dynamics. One clarification is that the rotational kinetic energy of the Explorer 1 decreased due to internal stresses, flexing and deformation of the structure (mostly this was from the whip-like antenna of the Explorer 1). Thus the rotational kinetic energy decreased (total energy of course is still conserved), but combining this with the conservation of angular momentum thus required the Explorer 1 should end up rotating around it's shorter axis/larger momentum of inertia.

Best,

Mike, Max, Dan, Simon, Doug

Thanks for viewing and commenting on our video. The Explorer 1 is an interesting example of rotational dynamics. One clarification is that the rotational kinetic energy of the Explorer 1 decreased due to internal stresses, flexing and deformation of the structure (mostly this was from the whip-like antenna of the Explorer 1). Thus the rotational kinetic energy decreased (total energy of course is still conserved), but combining this with the conservation of angular momentum thus required the Explorer 1 should end up rotating around it's shorter axis/larger momentum of inertia.

Best,

Mike, Max, Dan, Simon, Doug

Hi,

Your video was very interesting. I learned some things, got good ideas for future teaching, and enjoyed the process. Thanks.

I'd be grateful if you'd take a look at our video and give it a rating as a creator. I suspect that a rules change may happen, but ours is one of the majority not close to the 10 ratings needed to be considered for the finals. It's at the middle of the second row from the bottom if you sort alphabetically. Thanks if you get the chance.

James

Your video was very interesting. I learned some things, got good ideas for future teaching, and enjoyed the process. Thanks.

I'd be grateful if you'd take a look at our video and give it a rating as a creator. I suspect that a rules change may happen, but ours is one of the majority not close to the 10 ratings needed to be considered for the finals. It's at the middle of the second row from the bottom if you sort alphabetically. Thanks if you get the chance.

James

Hi James,

Thanks for your comments and we will definitely have a look at your video. Yes it does appear there was a rule change so that one must have a minimum of 10 ratings to be considered for the next round. This was the usual restriction for the essay contests run by FQXi so we were surprised when this did not appear as a requirement for the video contest. Probably an oversight.

One thing -- we did find your video by your name but the location you give "the middle of the second row from the bottom" so maybe the order in which videos arew displayed is different. Anyway we did find your video and will have a look.

Best regards,

Mike, Max, Simon, Dan, Doug

Thanks for your comments and we will definitely have a look at your video. Yes it does appear there was a rule change so that one must have a minimum of 10 ratings to be considered for the next round. This was the usual restriction for the essay contests run by FQXi so we were surprised when this did not appear as a requirement for the video contest. Probably an oversight.

One thing -- we did find your video by your name but the location you give "the middle of the second row from the bottom" so maybe the order in which videos arew displayed is different. Anyway we did find your video and will have a look.

Best regards,

Mike, Max, Simon, Dan, Doug

Hi,

About a rules change, I meant that the current rules aren't going to work if a whole lot of community members don't start rating videos soon and may need to be changed. I was vague. I didn't know that that rule had already been changed. The post below reassures me that I wasn't the only one who didn't know the tennis racket theorem. That's good to know. Thanks for taking a look at our video.

James

About a rules change, I meant that the current rules aren't going to work if a whole lot of community members don't start rating videos soon and may need to be changed. I was vague. I didn't know that that rule had already been changed. The post below reassures me that I wasn't the only one who didn't know the tennis racket theorem. That's good to know. Thanks for taking a look at our video.

James

Mike, Max, Dan, Simon and Doug,

Very interesting video! I didn't know about the "Tennis Racket Theorem", and I learned quite a lot. It was nice to see the actual experiments with tumbling boxes that illustrate the theorem. The real life example of Explorer I was also very interesting. I will certainly show parts of your video to my students when I discuss angular momentum!

Good luck in the contest!

Marc

P.S. If you have a chance to view, comment and vote on my trilogy of videos entitled "This Is Physics" --- where I try to convey the "fun of physics" by focusing on some of the greatest moments of its history --- it would be quite appreciated! (I think many of the participants in the contest have not yet realized that a video needs to get at least 10 community ratings to be considered for the final round... and there's only 5 days left to vote!)

Very interesting video! I didn't know about the "Tennis Racket Theorem", and I learned quite a lot. It was nice to see the actual experiments with tumbling boxes that illustrate the theorem. The real life example of Explorer I was also very interesting. I will certainly show parts of your video to my students when I discuss angular momentum!

Good luck in the contest!

Marc

P.S. If you have a chance to view, comment and vote on my trilogy of videos entitled "This Is Physics" --- where I try to convey the "fun of physics" by focusing on some of the greatest moments of its history --- it would be quite appreciated! (I think many of the participants in the contest have not yet realized that a video needs to get at least 10 community ratings to be considered for the final round... and there's only 5 days left to vote!)

Hi Marc,

Thanks for viewing our video and your comments. yes the tennis racket theorem is one of our favorite examples since one sets up the problem using the Euler equations (essentially the equations of motion for the rotations of a solid body) and then out of the mathematical analysis of these equations comes some very simple result that can be easily seen with any object having 3 distinct moments of inertia. The Wikipedia page for this

(http://en.wikipedia.org/wiki/Tennis_racket_theorem)

gives the basic set up but as mentioned the explanation would only make sense to someone who already knows what all the parameters mean. But given that this is the case one can then see why the long and short axis give stable wobbling around these axes and why the intermediate axis gives tumbling.

Also one warning if you use this for students the white board picture of the Explorer 1 could lead to the wrong impression that the direction of the angular changes since for artistic proposes we kept the orientation of the Explorer one the same. The animation of the Explorer 1 gives a more accurate representation of what happened -- the angular momentum (both magnitude and direction) remained the same while the Explorer 1 changed its orientation.

We will have a look at your videos and send comments as well. We had also thought to make a longer 3 segment version of our story but were working against the August 12th deadline which got extended to August 22nd.

Best regard and luck with the contest,

Mike, Max, Simon, Dan, Doug

Thanks for viewing our video and your comments. yes the tennis racket theorem is one of our favorite examples since one sets up the problem using the Euler equations (essentially the equations of motion for the rotations of a solid body) and then out of the mathematical analysis of these equations comes some very simple result that can be easily seen with any object having 3 distinct moments of inertia. The Wikipedia page for this

(http://en.wikipedia.org/wiki/Tennis_racket_theorem)

gives the basic set up but as mentioned the explanation would only make sense to someone who already knows what all the parameters mean. But given that this is the case one can then see why the long and short axis give stable wobbling around these axes and why the intermediate axis gives tumbling.

Also one warning if you use this for students the white board picture of the Explorer 1 could lead to the wrong impression that the direction of the angular changes since for artistic proposes we kept the orientation of the Explorer one the same. The animation of the Explorer 1 gives a more accurate representation of what happened -- the angular momentum (both magnitude and direction) remained the same while the Explorer 1 changed its orientation.

We will have a look at your videos and send comments as well. We had also thought to make a longer 3 segment version of our story but were working against the August 12th deadline which got extended to August 22nd.

Best regard and luck with the contest,

Mike, Max, Simon, Dan, Doug

This is a very interesting video; it's a topic I had seen before, but had never fully understood. I had never seen the example with the Explorer 1 satellite. Good explanations!

By the way, if you could watch and rate my video, "The Cool Physics of Refrigeration," that would be great. Thanks!

David

By the way, if you could watch and rate my video, "The Cool Physics of Refrigeration," that would be great. Thanks!

David

Hi David,

Thanks for your comments and we will certainly have a look and give comments on your video. There are two broad categories of videos: (i) those that discuss frontier type stuff and (ii) those (like our videos) that discuss more "bread and butter" physics. So in any case we will have a look.

Best regards,

Mike, Max, Dan, Simon, Doug

Thanks for your comments and we will certainly have a look and give comments on your video. There are two broad categories of videos: (i) those that discuss frontier type stuff and (ii) those (like our videos) that discuss more "bread and butter" physics. So in any case we will have a look.

Best regards,

Mike, Max, Dan, Simon, Doug

Very interesting concept to do a video on - I really enjoyed it!

If you get a chance I'd really appreciate it if you gave our video a watch and rated it too!

http://fqxi.org/community/forum/topic/2189

Thanks in advance,

Ian Harris

If you get a chance I'd really appreciate it if you gave our video a watch and rated it too!

http://fqxi.org/community/forum/topic/2189

Thanks in advance,

Ian Harris

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