1. Bridge Building Challenge Materials: 24 ft. of 3/32” balsa wood and one bottle of Elmer’s glue, scissors NO OTHER MATERIALS MAY BE USED Specifications: Free standing Only the allowed materials Maximum length: 22 cm Minimum length of deck AND minimum clearance between piers at base:14 cm Maximum width: 3 cm Minimum width of deck: 3cm Maximum height: 8 cm Minimum height: 5 cm Minimum vertical clearance at the center of the span: 5 cm for a minimum 3 cm width Must have a trapezoidal opening with minimum dimensions. Of course, it can be larger Channel bottom must be clear and open

2. Load Diagram Diagram drawn to scale of the bridge with all force vectors shown. Scale must be included By hand, this must be clean, neat, use a straight edge and your writing must be meticulous –Label: upper chord, lower chord, web members, joints, end post, span, load or weight and piers –For up to 4 extra points show where tensile and compressive stresses are on the members and discuss in paragraph. –See Handout on Trusses and Stresses in Members of Trusses

3. Testing Step 1: Load will be applied with a 3 cm X10 cm test block centered on the bridge. No side supports will be used. Bridges will be tested until failure unless otherwise requested after the grade requirement is met. Additional Step 2: A simulated paved roadway, 3 cm in width cut from a manila folder, will be placed on the freestanding bridge. A 1 kg mass must be able to roll across the bridge. Any bridge not able to withstand this test will be disqualified from further testing competition.

4. Credit: on time (5) Bridge stability. Stand up freely. (15) Bridge fulfilling requirements. (10) Neatness of construction. –Good craftsmanship: no glue drips, no dirty fingerprints, clean cuts use sand paper to clean up ends (10) Diagram drawn to scale of the bridge with all force vectors shown –Individually prepared (10) Paragraph paper explaining your reasoning for your particular design. The quality of writing is expected to be at the senior level. –Individually prepared Bibliography: MLS format on a Works Cited Page. If there is no works cited you will get zero credit for the paragraph. (5-10) Creativity: extra credit for design if explained on the diagram and paragraph

5. Participation Each student will be expected to fully participate in the conceptual discussion and construction. Participation is built into each of the categories for the group.If you sit back and enjoy the ride do not expect any points for the categories for group. For one absence you may make up your participation by come in in before and after school and at lunch. If you are absent for two of the three days after the presentation day, you will make your own bridge using the same requirements but you will use 13 g of toothpicks. You can use pointed or blunt. I recommend blunt end.