Science Fair ProjectLondon Bridges Falling DownKate Howard and Kira Koziak

Statement of ProblemWhich Truss Design supports the

most weight, the Warren or the Howe?

Project OverviewFor 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.

ResearchThe Warren Truss is the most

used design

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.

HypothesisThe Warren Truss will hold the

most weight because it distributes the weight more evenly than the Howe Truss.

MaterialsBalsa wood60cmx60cm block of Styrofoam4572cm of Plastic Wrap(150sq ft)Superglue gel1 piece of graph paperBlock and chainExacto knifeLarge bucketApprox. 10lbs of water1 pen or pencilTruss designs (1 Warren and 1 Howe)2 pairs of safety goggles

Procedure1. Gather supplies2. 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 wood5. 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 Trust11. Graph averages12. Compare and contrast

Procedure

Photos

Data and Observations

Category 1

Category 2

0 1 2 3 4 5 6 7 8 9 10WEIGHT HELD IN POUNDS

TRUSS TYPE

RED- TRIAL 1

YELLOW- TRIAL 2

BLUE- TRIAL 3

WARREN

HOWE

ConclusionThe 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.

Possible Experiment ErrorsSome 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.

Applications and RecommendationsI would recommend that other

people monitor how they build the bridges so that each bridge can be exactly like the others

Works Cited The Toothpick Bridge - Design and Build Strong

Toothpick Bridges. Web. <http://www.toothpickdesign.com/trusstoothpickbridges.htm>.