HONOLULU (HawaiiNewsNow)- Dr. V from Oceanit joins us to show how the design construction of a bridge is as important than what it is made from.
Dr. V Show: Paper Bridges
July 27, 2010
Things you need:
- Index cards
- Some books to make two stacks of the same height
- Pennies, either loose or in rolls
Stack your books so that you have two stack of the same height and place them about 4 inches apart. This will be the span of your bridge, or the area that your bridge will cross. Starting with just one index card, lay it flat across the gap between the books, keeping about ½ an inch of the card resting on the books. Slowly place pennies, one at a time, on your bridge. How many pennies will this bridge hold? Try making different shapes with your index card, like a rectangular or circular cross-section, arch, or even a pleated card. Which bridge holds the most pennies?
How does it work?
Your paper bridge may hold more pennies than you think it will. Different shapes have different structural strengths. This is a great experiment to see which shapes are strong and which ones are weak. There are really only three kinds of bridges, beam spans, like a log over a river, arches, which have been around since 1,000 B.C., and suspension bridges, like the Golden Gate Bridge in San Francisco. All the bridge you see are some form of one of these three bridges.