ENGINEERING ON A SHOESTRING
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Tops  - for time & speed 

  I have long been a fan of Newton disks, which show when the colors of the spectrum,  in the right proportion and speed will blend together and appear white.   With an optical tachometer that I bought  for less than $20 on eBay I found that the commercial disk needed to spin at about 3200 RPM to see the white effect.  I wondered if we could make a top that would spin fast enough to produce the white effect.   

Using a whole cutter and heavy cardboard I made many, many disks for our tests.   Fortunately, pencils are a good fit for the hole make by the whole cutter and if needed you can use tape to make the pencil slightly larger.  
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​Materials need                                                                                              Tools
heavy cardboard                                                                                            Drill motor
pencils                                                                                                               Hole cutter 
tape                                                                                                                    Stop watch - on cell phones
pennies                                                                                                              Optical tachometer - optional 
aluminum foil, shinny metalic tape or ribbon                                          Hot glue gun - optional 

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 Variations:
Size of disks
number of disks 
pencil size:  length,  short golf pencils 
Spinning point:  sharpened point or eraser end.  This had some some surprising results. 
Pennies for weight
Arrangements of weights towards the edge. Pennies can be taped to the outer edge. 

Teaching/Investigation tips
I set up some preliminary investigations to help 
      Place the disk high and low on the pencil (center of gravity) 
      Place  penny weighs close to the axis and near the edge
      
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 col
​​Image sources: 
- Newton's Disk  ​http://www.daviddarling.info/encyclopedia/N/Newtons_color_disk.html
- Optical Tachometer:  generic picture from simplemotor.com  
​- Hole saws:  harbor freight 
- Newton Wheel in color- ​www.fizzicseducation.com.a
- Newton Disk pattern:  ​http://etc.usf.edu/clipart/20100/20109/newtondisk_20109.htm
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  • Home
  • Design Process
  • About Us
  • Tops
  • Mini Hovercraft
  • Contact
  • Disclaimer
  • Stomp Rockets
  • Homopolar Motors
  • Weiser
  • Slide Show