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OBJECTIVE
TO DESIGN AND BUILD A BRIDGE WHICH CAN BE TESTED FOR
STRUCTURAL STRENGTH AND THEN ANALYZED FOR THE FORCES
INVOLVED
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MATERIALS
ROUND OR FLAT WOODEN TOOTHPICKS
ELMER'S WHITE GLUE
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INSTRUCTIONS
EACH STUDENT WILL RESEARCH BRIDGE DESIGNS FROM
LITERATURE OR ACTUAL STRUCTURES NOTING BRACING POINTS
AND REINFORCEMENTS AND HOW EACH DESIGN TAKES INTO
ACCOUNT GRAVITATIONAL AND LOAD FORCES AND THE
MATERIALS USED. EACH STUDENT WILL THEN DESIGN AND
BUILD A BRIDGE USING WOODEN TOOTHPICKS AND ELMER'S
WHITE GLUE
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SPECIFICATIONS
THE TOTAL WEIGHT OF THE FINISHED
BRIDGE CANNOT EXCEED 40 gm
ANY DESIGN CAN BE USED AS LONG AS THE ROADBED IS FLAT
AND UNOBSTRUCTED TO ALLOW A MATCHBOX CAR TO TRAVEL
ITS LENGTH.
THE BRIDGE MUST BE FREE STANDING AND ALLOW FOR A 2 cm
X 30 cm BOARD TO PASS UNDER THE BRIDGE WHILE IT RESTS
ON A FLAT SURFACE.
ONLY THE MATERIALS LISTED MAY BE USED TO BUILD THE
BRIDGE.
EXCESSIVE AMOUNTS OF GLUE MAY NOT BE USED AS PART OF
THE STRUCTURE, i.e. THE BRIDGE MAY NOT BE COMPLETELY
COVERED WITH GLUE.
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PROCEDURE
TO TEST EACH BRIDGE'S STRENGTH WE
WILL PLACE THE BRIDGE ONTO AND BETWEEN TWO
FLAT-TOPPED TABLES SPACED 25 cm APART.
AN 8" WOODEN DOWEL WITH A 1/2" DIAMETER IS
SET ACROSS THE MIDDLE OF THE ROADBED. TWO LOOPS OF
STRONG CORD ARE ATTACHED TO THE HANDLE OF A 5 gal
BUCKET. EACH LOOP OF CORD IS THEN LOOPED OVER EACH
END OF THE DOWEL TO SUPPORT THE BUCKET BELOW THE
BRIDGE. SAND OR WATER IS ADDED TO THE BUCKET UNTIL
THE BRIDGE BREAKS. THE BUCKET AND ITS CONTENTS ARE
THEN WEIGHED.
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RANKING
EACH BRIDGE WILL BE RANKED USING A
RATIO OF LOAD WEIGHT TO BRIDGE WEIGHT.
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Sample Plans for Tooth Pick
Bridges