Forces and Structures Flashcards
Forces and Structures
What is a combination structures
- combination of two or more structures
- house (frame + solid), CN Tower (frame + solid + shell)
what is a structure?
- Something made up of one or more parts put together that can support a load
- Every structure has a form and function
- Form = basic shape
- Function = it’s purpose
- Function may be easy to identify, example, a ladder. What is its function?
what is a human made structure?
- made by human
- buildings, bridges, cars, house, table
What is a natural structure?
- created by nature
- trees, nests, shells, skeletons
What is a solid structure?
- Usually solid all the way through
- Formed from one solid piece of material
- Weighs more than a hollow structure
- rocks, bricks, cement poles
What is a frame structure?
- A structure made of parts joined together
- The parts are called components
- Use less material that solid structures (makes them lighter)
- coral, spider webs, ladder, bike
Types of external forces
- Acts on a structure but is not part of the structure
- gravity, friction, tension
Types of internal forces
- One part of a structure acting on another
- Compression, Tension, Torsion, Shear
How can you strengthen a structure?
- you can make a structure stronger by adding more shapes onto it
- Adding more triangles into a triangle structure or adding triangles into a rectangular structure.
Why is a triangle considered the strongest shape?
- when force is put on a point, all weight/force is distributed between structure
What is stability?
- Means being able to stay balanced while you
experience forces - A measure of how resistant a structure is to being
knocked over - Depends on materials and construction techniques, as
well as centre of gravity
What is centre of gravity and how does it affect stability?
- The point at which a mass is equally balanced in all
directions - The location of the centre of gravity helps determine
how stable a structure is - the lower the centre of gravity is, the hard it will be to knock over the structure (ex. football players crouch when running so they don’t het knocked over easily)
What is structural stress? Give an example
- Books on the middle of a shelf may cause the
shelf to bend. This is called Structural stress
-When the books are removed the shelf goes back to it’s original shape.
What is structural fatigue? Give an example
- repeated stress over time might crack or warp the
structure (ex. a book shelf) leading to permanent changes. - permanent changes are called structural fatigue.
What is structural failure? Give an example
- if the structure eventually collapses, then that means that the external forces were too strong
- this is structural failure
Why do components fail sometimes?
- Shapes of components sometimes can not withstand
internal or external forces
Compression
- Force that squeezes or presses something together
Tension
- A force that stretches apart to expand or lengthen
Shear
- Force that pushes in opposite directions
Torsion
- the force that twists
Structures that contain (examples)
- Retaining wall, mug, shopping bag, nest
Structures that support (examples)
- Ladder, spider web, shelf
Structures that span a space (examples)
- bridge, docks, boardwalks
Structures that protect
- Helmet, bubble wrap, roof, shoes, animal den
Structures that make a task easier
- Rake, shovel
Shell structure (definition)
- A structure that has a solid outer surfaces and hollow inner area
- Lighter, used for protection
- Egg cartons, food cans and bottles, pipes, and clay pots
Frame structure (definition)
- A structure made of parts joined together
- The parts are called components
- Use less material that solid structures (makes them lighter)
- spiderwebs, skeletons, bridges, chairs
4 properties when describing forces
Magnitude: Strength of the force
Direction: direction the force is coming from
Plane of application: “Slice the force travels along
Point of application: location where the force meets the structure
Combonation structure
- a structure with more than one type of structure (frame, shell, solid)
- house (frame & solid) and CN tower (frame, solid, shell)
What is force
- A force is any push or pull
- Act on all structures.
- When being built, structures must be designed and built to withstand forces they will face.
- Understanding forces help people build and design better structures.
Universal Design
- Structures that are useful beyond their design
- Ex: Wheelchair ramps and automatic doors were designed for people in wheelchairs
- They are also useful for people using walkers, pushing strollers, and for people carrying heavy objects.
What is structural stress? Give an example
- Books on the middle of a shelf may cause the
shelf to bend. This is called Structural stress
-When the books are removed the shelf goes back to it’s original shape.
Failing for safety: how are some structures designed to fail for safety? Give examples
- some structures are known to be dangourous if they fail, so they are designed to fail
- ex. tempered glass. it is dsigned to break into a million little peices, so that you cant get hurt easily
The difference between a static and dynamic load
- a static load stays the same, while a dynamic load will change often
- ex. the weight of a building is a static load, but the weight of the people in it is a dynamic load
What is planned failure
- planned failure is when the structure has properties that help prepare and protect from failure
Structures that looks aesthetically appealing
- you can do this by using various shapes and colours
