External and internal forces

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# External and internal forces - PowerPoint PPT Presentation

External and internal forces. There are TWO types of forces that designers MUST consider when designing structures. External Forces: forces that act on a structure from the OUTSIDE Internal Forces: forces that act a structure from WITHIN. External forces.

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## PowerPoint Slideshow about ' External and internal forces' - nimrod

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Presentation Transcript
External and internal forces
• There are TWO types of forces that designers MUST consider when designing structures.
• External Forces: forces that act on a structure from the OUTSIDE
• Internal Forces: forces that act a structure from WITHIN
External forces
• What are some external forces you can think of?
• The most obvious external force is gravity
• External forces occur when……..
• You push a swing, pull an elastic or throw a ball
• External forces on buildings include…..
• Wind, earthquakes, weight of people on the floors of the building and the weight of the building itself

POINT OF APPLICATION:

The precise point at which the force is applied

PLANE OF APPLICATION:

An imaginary flat surface through which an applied force passes

****the point and plane of application make a difference in how an applied force affects a structure. See page 278 in your text

Examples of the 4 internal forces
• Tension
• Examples include: a stretched skipping rope, a trampoline, an electrical power line, a guitar string, the cables of a suspension bridge
• Once the particles pass their breaking point the objects are unable to return to their original shape
• Compression
• Examples include: kicking a soccer ball, step on the sole of your shoe, lay your head on a foam cushion.