Forces and Structures

Front

external force

Back

A force acting on an object or structure from the outside. Eg. gravity; wind; kicking a soccer ball

Front

internal force

Back

A force that acts on an object from the inside. Eg. tension in a stretched elastic; weight of room sitting on walls of building.

Front

dead load

Back

A permanent force acting on a structure, such as the weight of the structure itself

Front

live load

Back

A type of load that changes, such as people walking across a bridge, snow on a roof, etc.

Front

4 types of forces

Back

Tension (stretch), compression (squish), shear (tear), torsion (twist)

Front

lever

Back

A tool that changes the amount of force needed to move an object

Front

fulcrum

Back

The fixed point around which a lever pivots

Front

three ways in which materials fail

Back

Shear (one section slides over another at the weak point); bend/buckle (compression causes material to bend); torsion (twisting materials causes them to break/lose their structure)

Front

metal fatigue

Back

A weakening of metal due to stress, resulting in an accumulation of small cracks and eventually causing metal to break