Building a Self-Supporting Bridge

Today’s science experiment deals with physics! We are going to create a bridge without tape or glue that stands by itself and can support a lot of weight. This bridge was first designed for the Sultan of the Ottoman Empire in the early 1500’s by a man named Leonardo da Vinci. However, the bridge design was rejected, so the bridge was never built. Today we are going to create a mini version of the bridge using pencils and rubber bands.

What you need:

• 9 pencils
• 27 rubber bands

Steps:

• Attach 3 rubber bands to each pencil- one an inch from the end of the pencil on each side and one in the middle.

• Using this picture, try to create the da Vinci bridge on your own. The rubber bands help keep the pencils from sliding in some spots, but you may have to adjust the locations of some of the rubber bands. If you get stuck and need help building, click here for a helpful guide.

• Place weights and other items from around your house on top of the bridge. See how much weight yours can hold! Ours has 4 pounds on it in this picture.

How does the da Vinci bridge work?

When the bridge is first assembled, the pencils are slightly loose and can slide around because of the low weight of the pencils. When a load (such as the weights on our bridge) is applied, the central beam spreads the weight throughout the structure, and the beams become rigid. The force makes the pencil connections tighten, therefore increasing the stability of the bridge.