Forces Lab |
Materials Lab |
Loads Lab |
This lab simplifies the real-life properties of a selection of materials, in order to illustrate key concepts.
What you build a structure out of is just as important as how you build it! Different materials have vastly different properties. Click on a material at left to find out more about it, and put it to the test.
Type: Spruce (softwood)
Strengths: Cheap, lightweight, moderately strong
in compression and tension
Weaknesses: Rots, swells and burns easily
Bridges, houses, two- to three-story buildings, roller coasters
Example: Son of Beast -- Cincinnati, Ohio
You squeezed this block easily, but it took a lot of effort to make it break. Wood is cheap and pretty strong in compression. That's why people build houses out of wood!
It wasn't easy to break this block of wood because wood is strong when you pull it in the direction of its fibers. It would have been three times easier for you to break this block if you'd stretched it from the top and bottom, across the direction of its fibers.
Type: High-strength plastic fabric
Ingredients: Long chains of molecules
Strengths: Flexible, lightweight, long-lasting,
strong in compression and tension
Umbrellas, inflatable roofs over sports arenas
Example: Georgia Dome -- Atlanta, Georgia
Compared to steel, you squeezed this plastic block easily, but it took
a lot of effort to make it break. The long chains of molecules that make up plastic can be pulled and pushed in many directions without failing.
You stretched this plastic pretty far before it finally broke. The long chains
of molecules that make up plastic can be pulled in many directions without snapping. That's one of the reasons why circus tents are made of plastic fabric!
Type: Aluminum alloy
Ingredients: Aluminum with magnesium & copper
Strengths: Lightweight, doesn't rust, strong in compression and tension
Airplane wings, boats, cars, skyscraper "skin"
Example: Petronas Towers -- Kuala Lumpur, Malaysia
It was pretty hard for you to break this aluminum block. That's because the magnesium and copper inside this block makes it almost as strong as steel!
It wasn't easy to break this aluminum block. That's because aluminum, when combined with metals like magnesium and copper, is almost as strong as steel!
Type: Ordinary brick
Ingredients: Burned clay
Strengths: Cheap, strong in compression
Weaknesses: Heavy, weak in tension
Walls of early skyscrapers and tunnels, domes
Example: Original Thames Tunnel -- London, England
You had to push this brick very hard to make it crumble. Bricks are very strong in compression. That's why early houses were made of brick!
You pulled this brick apart easily! That's because bricks are very weak in tension.
Type: Fine-grain concrete
Ingredients: Cement, water, small stones
Strengths: Cheap, fireproof and weatherproof,
molds to any shape, strong in compression
Weaknesses: Cracks with temperature changes,
weak in tension
Early arch bridges and domes
Example: Pantheon - Rome, Italy
You had to squeeze this concrete block really hard to make it break. That's because concrete is very strong in compression.
You pulled apart the small stones and cement in this concrete block
easily. That's because concrete is weak in tension.
Type: Fine-grain concrete with high-strength steel
Ingredients: Steel bars hidden in concrete
Strengths: Low cost, fireproof and weatherproof, molds to any shape, strong in compression and tension
Weaknesses: Can crack as it cools and hardens
Bridges, dams, domes, beams and columns in skyscrapers
Example: Hoover Dam - Nevada/Arizona border
You had to squeeze this block really hard to make it break. That's because concrete and steel are both very strong in compression.
It was hard to pull this concrete block apart because the steel bars inside make it very strong in tension. That's why some of the tallest skyscrapers in the world are made of reinforced concrete.
Type: Cast iron
Ingredients: Iron with lots of carbon
Strengths: Molds to any shape, strong in compression
Weaknesses: Weaker than steel in tension, breaks without warning
Arch bridges, cannons, historic domes
Example: Iron Bridge - Shropshire, England
It wasn't easy for you to squeeze this cast-iron block. Cast iron is strong in compression. That's why early arch bridges were made of cast iron.
It was easy for you to pull this cast-iron block apart. That's because cast iron is brittle -- it snaps without warning.
Type: High-strength steel
Ingredients: Iron with a touch of carbon
Strengths: One of strongest materials used in construction, strong in compression and tension
Weaknesses: Rusts, loses strength in extremely high temperatures
Cables in suspension bridges, trusses, beams and columns in skyscrapers, roller coasters
Example: Sears Tower - Chicago, Illinois
You had to push extra hard on this steel block to make it bend and break. Steel is stronger than any other material in compression. That's why engineers choose steel beams and columns to support most skyscrapers.
You had to pull this block incredibly hard to make it break because steel is stronger than any other material in tension. That's why the cables in the Golden Gate Bridge are made of steel.
Flash version of this lab