Eratosthenes' Model
Eratosthenes' Model

 

Code Number: 8A05.30

Demo Title: Eratosthenes' Measurement of Earth's Radius

Condition: Excellent

Principle: Measuring the Radius of the Earth

Area of Study: Astronomy

Equipment: 

Eratosthenes' Model.

Procedure:

Place the model so that one of the pillars is pointed at the light source and gives no shadow.  Bend the cardboard and show that the other pillar produces a shadow whose size depends on the radius you have produced by bending the cardboard.

References:

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  • Jerry Webb and Roberta Bustin, "Eratosthenes Revisited", TPT, Vol. 26, #3, Mar. 1988, p. 154.
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  • Kevin Krisciunas et al., "The First Three Rungs of the Cosmological Distance Ladder", AJP, Vol. 80, #5, May 2012, p. 429.
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  • Dennis Rawlins, "Doubling your Sunsets or How Anyone Can Measure the Earth's Size with Wristwatch and Meterstick", AJP, Vol. 47, #2, Feb. 1979, p. 126.
  • Jearl Walker, "The Amateur Scientist: How to Measure the Size of the Earth with Only a Foot Rule or a Stopwatch", Scientific American, Vol. 240, #5, May 1979, p. 172.
  • "S-360. Sight Distance at Sea", DICK and RAE Physics Demo Notebook, 1993.
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  • Jim Glenn, "The Geometers", Scientific Genius: The Twenty Greatest Minds, p. 18 - 19.
  • Robert P. Crease, "Measuring the World: Eratosthenes' Measurement of the Earth's Circumference", The Prism and the Pendulum, p. 2.