Observations and results
Which bridge was able to hold more weight? Why do you think that is?
When all the materials and circumstances are the same, suspension bridges can span longer distances than simple beam bridges. This is because the bridge deck, or roadway, is supported from above using tension in the cables and compression in the towers rather than just from bases. Suspension bridges are also less rigid, so they can better withstand outside forces, such as earthquakes. Have you crossed beam bridges or suspension bridges? See what kind of bridges you can find in your area.
• Discard straws, string and tape
• Return weights
More to explore
"100 Years Ago: Engineering a City—New York City's Bridges," from Scientific American
"Crowds Walking Can Make a Bridge Sway," from Scientific American
Brooklyn Bridge Timeline, from PBS's Ken Burns
Golden Gate Bridge, from PBS's American Experience
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