PURPOSE: To illustrate how the center of mass position affects the stability of an arch.
DESCRIPTION: Identical blocks are piled up with successively greater fractions of their lengths (1/16, 1/14, 1/12, 1/10, 1/8, 1/6, 1/4, and 1/2) extending over the edge of the preceding block, as shown in the photograph. Even though the top block is entirely over the edge of the base, the center of mass of the system remains above the base, so the configuration is stable.
REFERENCES: (PIRA 1J11.20)
EQUIPMENT: Eighteen marked 2"x4" wooden blocks with wooden box bases, as photographed.
SETUP TIME: None. (Assembled in class.!)
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