
Triangles vs. Squares in Bridge Strength
Medium
Which shape holds more weight in a bridge: a triangle or a square? Bridges use basic geometric shapes to carry heavy loads. You build two small bridges from toothpicks and glue to test which shape is stronger.
First you make 18 triangles and 10 squares from toothpicks. After drying you connect the triangles into a truss (a repeating frame). You build a second truss from the squares. Then you place a bucket on top and add scoops of gravel. You count how many scoops it takes before the bridge collapses.
Hypothesis
The hypothesis is that if a bridge is built with triangle-shaped supports, then it will be stronger and hold more weight than a bridge built with square-shaped supports.
Method & Materials
You will make triangles and squares out of toothpicks and glue, then build two trusses with them. You will then connect the trusses to form a bridge and test how much weight it can hold.
You will need a box of flat toothpicks, craft glue, wood glue or Elmer's glue, cardboard, waxed paper, paper towels, a small bucket, and rock material such as gravel, pebbles, or sand.
Results
After testing the bridges, it was found that the bridge with triangle-shaped supports was able to hold more weight than the bridge with square-shaped supports. This shows that triangles are stronger than squares when it comes to distributing force.
Why do this project?
This science project is interesting because it shows how geometry can be used to build strong structures. It also shows how triangles are better than squares when it comes to distributing force.
Also Consider
Variations of this project could include testing different shapes, such as hexagons, or testing different materials, such as popsicle sticks.
Full project details
Additional information and source material for this project are available below.Related videos
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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