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  1. Welcome to Building Bridges

  2. Objective Design and engineer a bridge using 1/8 inch balsa wood to hold as much mass as possible over a ___________ span. 12 inch

  3. Construction 1. The overall width of the bridge may not exceed _______ inches. 3 2. The overall length of the bridge may not exceed _________ inches. 15

  4. 3. The bridge shall allow a 1inch wide x ¾ inch thick board to pass through it on the roadbed. 4. The bridge shall have no structures below the abutments that support the bridge.

  5. 5. The bridge shall allow a 3/8 inch bolt to pass through the center of the bottom of the bridge unobstructed (for testing).

  6. 6. The bridge shall be constructed entirely of 1/8-inch x 1/8-inch balsa wood. adhesive 7. Any common _____________ _____________may be used at the joints of the wood members. (glue only, not masking tape)

  7. 8. Adhesives may used _____ at joints. only 9. Wood joints may be _______ if desired. notched 10. The mass of the bridge may not exceed ___ grams. 40

  8. Competition • The ____ of the bridge will be • determined before testing. mass 2. All bridges will use the same testing device.

  9. 3. The bridge will be tested using a 1-1/2 inch wide x 10-inch long x ¾-inch thick wood block with a hole in its center for testing mechanism.

  10. 4. The bridge is placed on the bridge tester, with the span set at 12 inches. 5. The teacher will attach the testing device to the bridge.

  11. 6. When the testing mechanism is ready, the student will begin to add sand to the bucket at the rate he or she chooses. 7. There will be a 10 minute time limit on adding sand to the bucket.

  12. 8. The student will continue to add sand to the bucket until the bridge collapses and the bucket falls. 9. The mass of the sand will be measured.

  13. 10. The bridge supporting the greatest load is the winner. 11. In the event that the bucket is completely filled without breaking for more than one bridge, then, of those bridges, the one that has the least mass wins.