# Bridges: Human links and innovations

## CONTENTS OF CURRICULUM UNIT 01.05.02

- Narrative
- Background on Bridge Type
- Different Types of Beam Bridges
- Background on Physical Forces and Bridge Design
- Engineering Vocabulary:
- Mathematical Vocabulary
- Experiment 1: Understanding Force7 (1 Day)
- Experiment 2: Name that Load8 (1 Day)
- Experiment 3: Feel the Pressure (1 Day)
- Experiment 4: Tension (1 Day)
- Experiment 5: Sponge Beam (1 Day)
- Experiment 6: Toothpick Truss (1-2 Days)
- Experiment 7: Straw Shape (1-2 Days)
- Experiment 8: Paper Bridge (1-2 Days)
- Use of math in bridge designs
- Using math to make a scale model bridge.
- The Problem: (10-15 Days)
- Web Site
- Bibliography

### Unit Guide

## Bridging the Math Gap

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## Background on Physical Forces and Bridge Design

A member bearing weight is under compression. Hard stone, like granite, can withstand an enormous compressive force before changing shape. A member being pulled is under tension. Granite, under tension, will break apart under a small amount of strain. In fact, a long beam of unsupported stone will crack under its own weight. Compared to the massive amounts of dead weight carried by each pier, the weight of moving objects on a bridge is insignificant. If a diagonal is placed across a rectangular frame, the shape becomes rigid and forms two triangles. Triangles are the simplest figure whose shape can't be altered without changing the length of one or more of its sides.