Recommended for: Grades 3-8
Resource: Forces Lab
Media Type:
Flash Interactive
Length:
Size: 124.2 KB
Large structures must be able to resist many different kinds of forces. A structure's own weight and other loads it experiences squeeze, stretch, bend, and twist the structure -- sometimes all at once. This interactive activity from the Building Big Web site describes some of the most important forces a structural engineer must consider and illustrates the damage these forces can cause.
Supplemental Media Available:
Forces Lab (HTML Interactive)
Teachers' Domain, Forces Lab, published January 22, 2004, retrieved on ,
http://www.teachersdomain.org/resource/phy03.sci.phys.mfe.bbforces/
- Background Essay
- Questions for Discussion
- Standards
Forces are everywhere. They lift us up and drag us down; they push us forward and pull us back. Whether it's getting out of bed in the morning, running a marathon, or hammering a nail, forces are at work in all the things we do. But forces are also acting on objects and structures that seem never to move at all.
Because we feel forces most obviously when we're very active, it may be surprising to learn that structures such as buildings and bridges withstand tremendous forces simply standing where they are built. A structure's own weight pushes down with nearly unimaginable force, while, at the same time, the ground supporting a structure pushes up with equal force. In addition, the weight and movement of equipment, vehicles, and people, and environmental factors such as temperature change, wind, and movement of the earth, combine to challenge structures further.
A structure's parts are constantly being squeezed, stretched, bent, and twisted. However, the design of these parts and their position relative to one another serves to balance these forces. The deck of a bridge, for example, is pulled downward by the force of gravity. The weight of the deck, in turn, pushes downward on the columns beneath it and pulls downward on the cables attached to it. In opposition, the columns and cables push and pull up on the deck with a force equal and opposite to that of the force of gravity. This keeps the deck and the rest of the structure in a state of equilibrium, and when forces cancel each other out in such a way, an object or structure maintains its shape and stays in place.
Because we feel forces most obviously when we're very active, it may be surprising to learn that structures such as buildings and bridges withstand tremendous forces simply standing where they are built. A structure's own weight pushes down with nearly unimaginable force, while, at the same time, the ground supporting a structure pushes up with equal force. In addition, the weight and movement of equipment, vehicles, and people, and environmental factors such as temperature change, wind, and movement of the earth, combine to challenge structures further.
A structure's parts are constantly being squeezed, stretched, bent, and twisted. However, the design of these parts and their position relative to one another serves to balance these forces. The deck of a bridge, for example, is pulled downward by the force of gravity. The weight of the deck, in turn, pushes downward on the columns beneath it and pulls downward on the cables attached to it. In opposition, the columns and cables push and pull up on the deck with a force equal and opposite to that of the force of gravity. This keeps the deck and the rest of the structure in a state of equilibrium, and when forces cancel each other out in such a way, an object or structure maintains its shape and stays in place.
Loading Standards
Teachers' Domain is proud to be a Pathways portal to the National Science Digital Library.
See Also:
K-12 Subject:
Applying the Design Process
Construction Technologies
Pushes and Pulls
Tension and Compression
Lesson Plans Using this Resource:
Source: Building Big Web site
This resource can be found on the Building Big Web site.
Resource Produced by:
Collection Developed by:
Collection Funded by:
