1. Science Fair Project London Bridges Falling Down Kate Howard and Kira Koziak

2. Statement of Problem Which Truss Design supports the most weight, the Warren or the Howe?

3. Project Overview For our project we built bridges out of balsa wood in two designs, The Warren Truss or the Howe Truss. Then we tested them by hanging a bucket from them and measuring in pounds how much water it held.

4. Research The Warren Truss is the most used design

5. Variables Independent- the truss design Dependent- weight each truss holds Constants- glue, bucket, wood, bucket securer, type of sand, spot where we hang it, length of bucket to ground, chain, type of styrofoam, person who pours sand Control- Warren Truss. This is logical because it is the most used truss design.

6. Hypothesis The Warren Truss will hold the most weight because it distributes the weight more evenly than the Howe Truss.

7. Materials Balsa wood 60cmx60cm block of Styrofoam 4572cm of Plastic Wrap(150sq ft) Superglue gel 1 piece of graph paper Block and chain Exacto knife Large bucket Approx. 10lbs of water 1 pen or pencil Truss designs (1 Warren and 1 Howe) 2 pairs of safety goggles

8. Procedure 1. Gather supplies 2. Wrap the 62cm x 60cm block of Styrofoam completely in plastic wrap with large sheet of graph paper under the plastic wrap. 3. Draw a Howe design of one piece and a Warren design of another. These will be what you use as a guide so all of your bridges will be the exact same size. 4. Build three of the Warren Trust designs. Make sure to leave a big enough hole at the top to fit a chain through but small enough to hold the block of wood 5. Build three of the Howe Trust designs. Make sure to leave a big enough hole at the top to fit a chain through but small enough to hold the block of wood 6. Break one trust by laying it across two tables and hanging the chain with the block of wood from it. Hang the bucket from the chain and slowly pour sand into the bucket. 7. Once the trust breaks weight how much sand the trust held and record observations and chart. 8. Repeat steps 6 and 7 for all five other trusts. 9. Graph all trials 10. Find the average of Warren Trust and average of Howe Trust 11. Graph averages 12. Compare and contrast

9. Procedure

10. Photos

11. Data and Observations

12. Conclusion The Truss that held the most weight on average was the Howe Truss. The Howe Truss’ average weight held was 8.27lbs and the Warren Truss’ average weight held was 7.13lbs.

13. Possible Experiment Errors Some possible experiment errors were gluing and it was hard to monitor how they were being built so it was hard to build each one the exact same way.

14. Applications and Recommendations I would recommend that other people monitor how they build the bridges so that each bridge can be exactly like the others

15. Works Cited The Toothpick Bridge - Design and Build Strong Toothpick Bridges. Web..