Spencer Disks


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 Code Number :   4A30.40  

Disclaimer:

Reprinted by permission of Dick Berg, University of Maryland, for use on this website.

The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources.

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Condition :   Good   
Principle :   Expansion & Contraction with Temperature Variation  
Area of Study :  Heat & Fluids  
Equipment :   Spencer Disks - Jumping Disks (bimetal disks), aluminum block.

Procedure :   Warm the jumping disks with your hand and press it to the click position. Set the disk on a cool level surface. In a few seconds the transfer of heat from the disk to the level surface will cause the bimetal disk to snap back to its original position causing the disk to jump into the air as it does so.

This demo may be enhanced by using an aluminum block heat sink that has been placed in the freezer for several hours.

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Websites


The Story of the Spencer Disk.

http://members.aol.com/spencerlab/history/al/al.htm

 

   References

Ed McNell,  "Newton's Laws with Jumping Disks,"  TPT, Vol. 26, # 5, p. 308, (May 1988).

 

Ha-11:  Freier and Anderson, A Demonstration Handbook for Physics.

 

H-122:  "Jumping Disks,"  DICK and RAE Physics Demo Notebook.

 

Robert Ehrlich,  "Bimetallic Jumping Disks,"  Turning the World Inside Out, p. 114-116.



Mail Questions and Comments to:  Dale Stille