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FPF Videos




Videos for the FPF Demonstrations

This page incorporates links to the short videos illustrating the concepts for the Fun Physics Facts for the Family Demonstrations...
(The longer podcasts of the FPF Demonstrations themselves have been removed because they recorded the short video clips of copyrighted materials that I used in an educational classroom setting during the lectures. For instance, during the Anti-Antigravity talk we watched a 2 minute segment from the BBC "Heretic" documentary in order to learn what Eric Laithwaite was claiming as gyroscopic antigravity. We used this segment to then learn how to argue against such antigravity claims. But since this segment was recorded in the lecture podcast, the podcast is not included on this website that is available to the general public.)



  1. Astronaut Turn Around Conservation of Angular Momentum:
    1. Here is a video (Astronaut-Turn_Around_Cons_L-1080p.mov) demonstrating the issues surrounding conservation of angular momentum.
    2. Click on the following link to watch the video on YouTube: http://youtu.be/VUueiewb-b8
    3. Description of the video: This video first shows Sandy attempting to spin around while seated on a turntable by swinging her arms. Her arms go one way while her torso goes the other way -- her net zero angular momentum is conserved. Secondly, Sandy pushed off against a chair, now she can change her angular momentum through the action of the external force. And lastly, if two individuals, both on turntables, push off against one another then their net angular momentum remains zero.
  2. Astronaut Turn Around by Rope:
    1. The following video (Astronaut-Turn_Around_Rope-1080p.mov) shows this scheme where m_p is simply a knot at the end of a rope.
    2. Click on this link to watch the video on YouTube: http://youtu.be/yI5RuUUOoPE
    3. Description of the video's experiments: This video demonstrates the above method for an astronaut to turn around by swinging a rope above her head. When the rope is revolved in one direction, the body must rotate in the opposite direction in order to conserve angular momentum.
  3. Astronaut Turn Around by Jug:
    1. Following is a video (Astronaut-Turn_Around_Jug_NoGershwin-1080p.mov) demonstrating this method for an astronaut to turn herself around.
    2. Click on this link to watch the video on YouTube: http://youtu.be/sXe2AO4JKxs
    3. Description of the video's experiments: This video shows a water jug being revolved in front of the body. In order to conserve angular momentum, the body must then rotate in the opposite direction.
  4. Astronaut Turn Around by Rotor:
    1. Following is a video (Astronaut-Turn_Around_Rotor-1080p.mov) demonstrating this method for an astronaut to turn herself around.
    2. Click on this link to watch the video on YouTube: http://youtu.be/O1JbldH_ADs
    3. Description of the video's experiments: This video shows a different type of astronaut turn around methodology employing a gyroscope. The angular momentum vector of the gyroscope is constant (conserved) unless acted upon by a net torque. The torque changes the angular momentum. Thus, the astronaut may turn around by applying a torque to the axle of the rotating rotor, as demonstrated in this video.




  1. Newton's Law Explanation, Part I Gyroscopic Precession:
    1. The following video (Gyroscope-Newtons_Law_Explanation_Part_I-1080p.mov) explains and demonstrates the Newton's Law Explanation for the precessional motion of a gyroscope. This explanation predicts the directions of the precession when a torque is applied to the gyroscope's axle as well as explains why the rotor does not simply "fall over" under the influence of gravity.
    2. Click the following link to view the video on YouTube: http://youtu.be/33amqcZXeus
    3. Description of the video's experiments: This video discusses the Newton's Law Explanation, based upon Newton's First Law of Motion, for the precessional motion of a gyroscope. It then demonstrates that this explanation predicts the correct direction of the precession as well as the fact that the gyroscope does not "fall over".
  2. Gyroscope Precession:
    1. Here is a video (Gyroscope-Precession-1080p.mov) demonstrating that a greater torque produces a faster precession and that a faster rotor spin rate yields a slower precession.
    2. Click on the following link to view the video on YouTube: http://youtu.be/dwU3veKRH88
    3. Description of the video's experiment: This experiment characterizes the functional dependency of the precession rate on both the torque and the rotor spin rate. In words, a greater torque produces a faster precession, and a slower rotor spin rate yields a faster precession rate. The precession rate is found to be directly proportional to the torque and inversely proportional to the rotor spin rate (see the equation below).
  3. Newton's Law Explanation, Part II Gyroscopic Precession:
    1. This video (Gyroscope-Newtons_Law_Explanation_Part_II-1080p.mov) provides the Second Law extension to the Newton's Law Explanation for the behaviors of a gyroscope. It shows how Newton's Second Law may be used to find the functional dependencies of the precession rate on the applied torque and the rotor spin rate.
    2. Click this link to view the YouTube video: http://youtu.be/BfqTvRi0YvA
    3. Description of the video's experiments: This video discusses the extension of the Newton's Law Explanation, based upon Newton's Second Law of Motion, for the precessional motion of a gyroscope. It describes how the Second Law predicts the functional dependencies of the precessional rate on the torque and the rotor spin rate. In particular, the precessional rate is directly proportional to the torque and inversely proportional to the rotor spin rate. The video then shows demonstrations of these torque and rotor spin rate effects on the precessional motion.
  4. Vertical Gyroscope Precession:
    1. Here is a video (VerticalGyroscope-Precession-1080p.mov) demonstrating what happens in for this vertical gyroscope when it's rotor is spun in both directions.
    2. Click on the following link to the YouTube video: http://youtu.be/st7Us-DHclY
    3. Description of the video's experiments: This video shows the precessional motions of a vertically oriented gyroscope when its rotor is spun in both directions. When the rotor spins clockwise, the precessional motion is also clockwise, and vice versa.
  5. Gyroscope Precession with Counterweight:
    1. The following video (Gyroscope-Precession_Counterweight-1080p.mov) demonstrates what happens when the gyroscope is spun in both directions and the spindle is twisted around.
    2. Click on the following link to view the video on YouTube: http://youtu.be/VTTZ6JwgD94
    3. Description of the video's experiments: This video shows a counterweighted gyroscope. When the direction of the gyroscope's rotor matches the direction of the twist around the spindle, the gyroscope "lifts". When these directions are opposite, the gyroscope "drops".
  6. Horizontal Gyroscope Precession:
    1. The following video (HorizontalGyroscope-Precession-1080p.mov) shows the complications that arise when the gyroscope is not counterweighted. Our Newton's Law Explanation is still sufficient to predict this behavior.
    2. Click on the following link to view the video on YouTube: http://youtu.be/vOBv0UzuReo
    3. Description of the video's experiments: This video shows a gyroscope whose axle is horizontal. The gyroscope is not counterweighted, so the gravity force on the rotor applies a torque to the gyroscope's axis of rotor spin. This torque produces an initial precessional motion. Additional applied torques to the spindle axis then speed up the initial precessional motion and "lift" the gyroscope, or slow down the initial precession motion and "drop" the gyroscope.
  7. Double Gyroscope Precession:
    1. The following video (DoubleGyroscope-Precession-1080p.mov) demonstrates the solutions for the double gyroscope.
    2. Click this link to view the video on YouTube: http://youtu.be/vGun5athdfg
    3. Description of the video's experiments: In this video two gyroscopes mounted on a common axis are spun in both the same direction and in opposite directions. The video shows what happens in both cases when the gimbal mount is twisted around.
  8. Gyroscope Suspended on a String:
    1. The following video (Gyroscope-String_Suspensions-1080p.mov) demonstrates what happens when the gyroscope is suspended from a string at two alternative locations.
    2. Click on the following link to view the video on YouTube: http://youtu.be/tCjjaavBfE4
    3. Description of the video's experiments: This video shows a gyroscope suspended from a string at two alternative locations. When the gyroscope is suspended along its axis, precession occurs and the gyroscope may be lifted by the string. When the gyroscope is suspended at a point perpendicular to the axis, no precession occurs and the gyroscope simply falls off the string.


  1. Schuler's Pendulum: Too Short, Too Long Periods
    1. Here is a video (SchulerPendulum-AltT_AgtT-1080p.mov) explaining and demonstrating the short period and infinite period pendulum behaviors under the action of perturbing accelerations.
    2. Here is a link to the video on YouTube: http://youtu.be/7qUPY6GZWL8
    3. Description of the video's experiment: In this video a pendulum having less than a second period is perturbed by accelerations at it pivot. When the accelerations are small, the pendulum bob keeps up with the acceleration. When the perturbation is large, the bob cannot keep up and thus lags behind. So a pendulum with a 1 second period would not keep a platform horizontal in the face of perturbing accelerations. At the other extreme, we consider a pendulum having an infinite period. Now any perturbation leaves the pendulum in its present orientation. This is good and bad, it is good because the pendulum does not have to "catch up" to the perturbation of the pivot, but it is bad because once the platform has moved sideways under the influence of the perturbing acceleration, it is no longer horizontal because of the curvature of the Earth's surface. So, an infinite period pendulum does not maintain the horizontal platform. So, is there a pendulum of some special period that can keep a horizontal platform horizontal in the face of random perturbing accelerations of its pivot?
  2. Schuler's Pendulum: Instantaneous Center of the Baseball Bat:
    1. The following video (SchulerPendulum-Instantaneous_Center_NoGershwin-1080p.mov) demonstrates the Instantaneous Center for a baseball bat.
    2. Here is a link to the video on YouTube: http://youtu.be/0FcjqHpnpFQ
    3. Description of the video's experiment: In this video a baseball bat is struck at three different locations along its length by a rubber mallet. When the bat is struck near to the hand grip, the grip quickly moves to the side out of the Sandy's fingers. A slow motion repeat of the video clearly shows the grip moving horizontally after the mallet strike. But when the bat is struck at its "sweet spot", the grip does not move horizontally, rather the bat rotates around the point at the grip. This is the instantaneous center, the point about which the bat rotates when struck. Again, slow motion clearly illustrates this rotation without horizontal motion. A third mallet strike at an intermediate point produces both motion and rotation.
  3. Gyrocompass Demonstration with Sandy:
    1. In the following video (Gyrocompass-Demonstration_Sandy-1080p.mov), Sandy demonstrates how the gyrocompass's axle will precess whenever a torque is applied to the axle by rotation about a vertical axis. But when the gyrocompass's axle is already vertical and thus aligned with the rotation axis, then there is no torque on the axle and hence no precession of the gyrocompass's axle.
    2. Here is a link to the video on YouTube: http://youtu.be/nErU-4cBO-8

      Description of the video's experiment: In this video Sandy supports the weight of the bicycle wheel rotor. She does not keep it from moving, in other words, she allows the wheel to precess if it wishes to do so. Sandy first stands on the lazy susan turntable with the bicycle wheel not rotating. As I spin the lazy susan turntable, the non-rotating wheel has no tendency to precess, so its axle remains horizontal as I rotate the turntable. Next the wheel is spun up to a high angular velocity and Sandy holds its axle in a horizontal direction. Now when I rotate the turntable, the wheel attempts to precess about a perpendicular axis. Sandy allows this precession to occur (she only supports the weight of the wheel), as we clearly can see. When I reverse the direction of the turntable, what happens? Watch the video to find out. And lastly Sandy holds the spinning wheel with its axle in a vertical direction. Now the wheel's axis and the turntable's axis are parallel, thus there is no net torque applied to the wheel's axle by the rotation of the turntable and hence the wheel does not precess in this situation.


  4. Gyrocompass Demonstration:
    1. Here is a video (Gyrocompass-Marvelous_Machine-1080p.mov) providing the answer.
    2. Here is a link to the video on YouTube: http://youtu.be/2SENzmIrQNM
    3. Description of the Video's Experiment: Notice that at the start of the video the gyroscope's rotor is not spinning, then as the platter is rotated the rotor's axis rotates around with the platter. It does not point in a fixed direction, rather it is fixed relative to the platter and thus rotates with the platter. When the gyroscope's rotor is spinning, however, the rotor axis appears to point in a fixed direction as the platter is rotated. But a careful observation shows that the rotor's axis is in fact precessing around some fixed axis. The question is, what fixed axis? Friction dampens the amplitude the precession so that it disappears and when the precession's amplitude vanishes the rotor's axis is pointing in a direction parallel to the platter's rotation axis. If there were no friction, then the rotor would continue to precess around the platter's rotation axis.
    4. What happens when the platter rotation direction is reversed? As the video shows, the gyroscope's rotor axis reverses direction (the gyroscope turns over) and friction settles it once again parallel to the platter rotation axis but now pointing in the opposite direction.
    5. You have to imagine in your mind that the lazy susan platter in the above video is the Earth spinning around its polar axis. You have to imagine that the tilt of the platter resting on the book and the additional tilt induced by the Altoids can represents the tilt of the gyrocompass's horizontal platform caused by its latitude position on the Earth's surface. You then recognize that the gyroscope's axis precesses until it points in the same direction as the spin axis of the platter -- this is analogous to the gyrocompass pointing true North on the Earth's surface (in other words, in the direction of the Earth's spin axis). This is the mechanism for how a gyrocompass operates. There is a difference, however, and that is the fact that the gyroscope's axle in the gyrocompass is restricted to a horizontal plane by Schuler tuning. This restriction does not allow the gyrocompass's axis to align with the Earth's spin axis (excepting at the Equator), rather it produces a precessional motion whose period is precisely the Earth's spin rate (23h 56m 4.09s) thus keeping the gyrocompass's axis pointing in the true North direction!!!!



  1. Gyroscope - No Weight Loss:
    1. Here is a video (Gyroscope-No_Weight_Loss-1080p.mov) of the wheel weighings.
    2. Click the following link to view the video on YouTube: http://youtu.be/4VX-YWoNm10
    3. Description of the video's experiment: In this video clip a spring balance scale is employed to measure the weight of the bicycle wheel. When the wheel is not spinning it hangs vertically from the scale and weighs 30N. If we support the axle opposite to the balance scale on the back of a chair, the scale reading drops by a factor of 2 to 15N (the chair supports half of the weight and the scale supports the other half). When the wheel is spinning, it appears that some mysterious force is "holding up" the opposite side of the axle, but instead of the scale reading 15N it reads the full weight of 30N.






Copyright (c) 2011 Craig G. Shaefer, all rights reserved.

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/groups/fun_physics_facts/search/index.rss?sort=modifiedDate&sortDirection=reverse&tag=fpf demolist/groups/fun_physics_facts/search/?sort=modifiedDate&sortDirection=reverse&tag=fpf demoFPF DemonstrationsCustomTagSidebarCustomTagSidebar?sort=modifiedDate&sortDirection=reverse&tag=fpf demo0/groups/fun_physics_facts/sidebar/CustomTagSidebarmodifiedDate5CustomTagSidebarreversefpf demoFPF Demonstrationscustom/groups/fun_physics_facts/search/index.rss?tag=hotlist/groups/fun_physics_facts/search/?tag=hotWhat’s HotHotListHot!?tag=hot5/groups/fun_physics_facts/sidebar/HotListcraigshaeferCraig Shaefer2016-11-27 17:50:13+00:002016-11-27 17:50:13updated33Added tag - jww691craigshaeferCraig Shaefer2014-12-18 15:49:24+00:002014-12-18 15:49:24addTag32Updated PDFs...craigshaeferCraig Shaefer2012-06-18 12:30:02+00:002012-06-18 12:30:02updated31Added tag - hotcraigshaeferCraig Shaefer2012-02-16 16:23:34+00:002012-02-16 16:23:34addTag9Added tag - oscillatorcraigshaeferCraig Shaefer2012-02-16 15:44:31+00:002012-02-16 15:44:31addTag3Added tag - electronicscraigshaeferCraig Shaefer2012-02-16 15:44:26+00:002012-02-16 15:44:26addTag2wiki2016-11-27T17:50:13+00:00groups/fun_physics_facts/wiki/c83abFalseElectronics/groups/fun_physics_facts/wiki/c83ab/Electronics.htmlCraig Shaefer6 updatesElectronics Fun Physics_Facts <-- click to return to Main page. Puzzlers: 8 (Electrodynamics) <-- click to...Falsecraigshaefer2016-11-27T17:50:13+00:00craigshaeferCraig Shaefer2016-11-27 17:48:26+00:002016-11-27 17:48:26updated72Added YouTube Screen Shot to PDF...craigshaeferCraig Shaefer2013-04-16 11:44:31+00:002013-04-16 11:44:31updated70Added Note 9: Our Proposed Mechanism is valid!craigshaeferCraig Shaefer2013-03-30 14:22:10+00:002013-03-30 14:22:10updated69add equations to alternative mechanismcraigshaeferCraig Shaefer2013-02-04 07:17:16+00:002013-02-04 07:17:16updated67Added tag - precessioncraigshaeferCraig Shaefer2013-01-23 13:34:06+00:002013-01-23 13:34:06addTag35Added tag - cycloramic appcraigshaeferCraig Shaefer2013-01-23 02:37:49+00:002013-01-23 02:37:49addTag32Added tag - gyroscopecraigshaeferCraig Shaefer2013-01-23 02:37:26+00:002013-01-23 02:37:26addTag31Added tag - hotcraigshaeferCraig Shaefer2013-01-23 02:37:10+00:002013-01-23 02:37:10addTag30craigshaeferCraig Shaefer2013-01-23 02:24:38+00:002013-01-23 02:24:38updated29wiki2016-11-27T17:48:27+00:00groups/fun_physics_facts/wiki/0702bFalseGyroscope Precession: Cycloramic.app/groups/fun_physics_facts/wiki/0702b/Gyroscope_Precession_Cycloramicapp.htmlCraig Shaefer9 updatesGyroscope Precession: Cycloramic.app [The CM-Gyroscope_Cycloramic_app.pdf file provided below contains the full and complete derivation of the quantitative formulae and q...Falsecraigshaefer2016-11-27T17:48:27+00:00craigshaeferCraig Shaefer2016-11-27 17:47:43+00:002016-11-27 17:47:43updated75Added tag - nutationcraigshaeferCraig Shaefer2011-11-26 15:52:32+00:002011-11-26 15:52:32addTag11Added tag - gyroscopecraigshaeferCraig Shaefer2011-11-26 15:52:25+00:002011-11-26 15:52:25addTag10Added tag - hotcraigshaeferCraig Shaefer2011-11-26 15:52:18+00:002011-11-26 15:52:18addTag9wiki2016-11-27T17:47:43+00:00groups/fun_physics_facts/wiki/25668FalseGyroscope Precession and Nutation/groups/fun_physics_facts/wiki/25668/Gyroscope_Precession_and_Nutation.htmlCraig Shaefer4 updatesGyroscope Precession and Nutation This is a work in progress...please do not read until I am finished. Thanks [The CM-Gyroscope_Nutation.pdf file provided below...Falsecraigshaefer2016-11-27T17:47:43+00:00craigshaeferCraig Shaefer2016-11-27 17:41:49+00:002016-11-27 17:41:49updated170Added tag - puzzlerscraigshaeferCraig Shaefer2010-12-18 22:52:32+00:002010-12-18 22:52:32addTag92Added tag - hotcraigshaeferCraig Shaefer2010-12-18 21:00:05+00:002010-12-18 21:00:05addTag81Added tag - fpf4tfcraigshaeferCraig Shaefer2010-12-18 20:59:59+00:002010-12-18 20:59:59addTag80wiki2016-11-27T17:41:49+00:00groups/fun_physics_facts/wiki/0f83dFalsePuzzlers/groups/fun_physics_facts/wiki/0f83d/Puzzlers.htmlCraig Shaefer4 updatesPuzzlers Fun Physics_Facts <-- click to return to Main page. Puzzlers These puzzlers are to test your...Falsecraigshaefer2016-11-27T17:41:49+00:00craigshaeferCraig Shaefer2013-08-28 14:24:59+00:002013-08-28 14:24:59updated9Added tag - hotcraigshaeferCraig Shaefer2012-07-31 12:48:58+00:002012-07-31 12:48:58addTag5wiki2013-08-28T14:24:59+00:00groups/fun_physics_facts/wiki/30897FalseNews/groups/fun_physics_facts/wiki/30897/News.htmlCraig Shaefer2 updatesNews Fun Physics_Facts <-- click to return to Main page. ...Falsecraigshaefer2013-08-28T14:24:59+00:00hot/groups/fun_physics_facts/search/index.rss?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomelist/groups/fun_physics_facts/search/?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomeRecent ChangesRecentChangesListUpdates?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcome0/groups/fun_physics_facts/sidebar/RecentChangesListmodifiedDateallRecent ChangesRecentChangesListUpdateswiki/welcomeNo recent changes.reverse5searchlist/groups/fun_physics_facts/calendar/Upcoming EventsUpcomingEventsListEvents1Getting events…