D Structures and Forces Flashcards
structure
- an object that provides support
- can be made of one or more parts
- could be large or small
structural strength
- capacity to hold itself up as well as any weight added to it
structural stability
- ability to maintain its position even when it is being acted on by a force
solid structure
- formed from one solid piece or solid combination of pieces
frame structure
- made up of a rigid arrangement of parts fastened together (you can see gaps between the parts such as in a wheel)
shell structure
- solid outer surface and hollow inner area
What was the main function of the benches that was overlooked in the design task?
Their function was to provide comfortable, inviting seating.
What materials were used to build the benches?
Block-like concrete.
What was the primary concern raised by the parks commission after the benches were installed?
Few people ever use the benches because they are unappealing and uncomfortable.
True or False: The design focused too much on durability and security.
True.
Fill in the blank: The benches were designed to be _______ and secure.
[durable]
What profession is the person designing the benches?
Landscape designer.
What was the consequence of not considering the benches’ main function?
The benches were rarely used.
What is an important consideration in the design of public seating?
Comfort and appeal.
What did the landscape designer prioritize in their bench design?
Durability and security.
What is the primary function of an airplane?
Movement and shelter
An airplane serves to transport people and goods while providing a space for them during travel.
What is the primary function of a train?
Movement and shelter
A train can transport both people and cargo, offering protection during transit.
Why is it important for a designer to know all functions of a planned structure?
To design a structure that will be used effectively
Understanding the functions helps in creating a structure that meets user needs.
What human need does an inukshuk meet?
Expresses joy and much happiness
Inukshuit are symbols of Inuit culture and convey positive feelings.
What additional role do many types of inukshuit serve?
Provide valuable information for travellers
Inukshuit can act as navigational aids in the Canadian North.
What are the necessary characteristics for inukshuit to fulfill their role?
Clearly visible, stable, and strong
These attributes ensure that inukshuit can effectively guide and inform travellers.
What is the primary function of an airplane?
Movement and shelter
An airplane serves to transport people and goods while providing a space for them during travel.
What is the primary function of a train?
Movement and shelter
A train can transport both people and cargo, offering protection during transit.
Why is it important for a designer to know all functions of a planned structure?
To design a structure that will be used effectively
Understanding the functions helps in creating a structure that meets user needs.
What human need does an inukshuk meet?
Expresses joy and much happiness
Inukshuit are symbols of Inuit culture and convey positive feelings.
What additional role do many types of inukshuit serve?
Provide valuable information for travellers
Inukshuit can act as navigational aids in the Canadian North.
What are the necessary characteristics for inukshuit to fulfill their role?
Clearly visible, stable, and strong
These attributes ensure that inukshuit can effectively guide and inform travellers.
What common aspect do all successful technological solutions share?
They pay close attention to function.
Functionality is crucial in solving technological problems.
Who is the Canadian inventor mentioned in the text?
Norman Breakey.
Norman Breakey invented the hand-held paint roller.
What problem did Norman Breakey aim to solve in 1940?
How to paint a large wall quickly and inexpensively.
Traditional methods like paint brushes were slow and wasteful.
What was one of the main considerations for Breakey’s design of the paint roller?
It had to be light enough for people to handle.
Ease of use in various spaces was also important.
What is the primary function of the hand-held paint roller invented by Breakey?
To allow paint to be rolled on quickly and smoothly.
This innovation improved efficiency in painting.
Fill in the blank: The hand-held paint roller is used by _______ and do-it-yourself painters all over the world.
[professional painters]
True or False: The hand-held paint roller was designed to be expensive and complex.
False.
It was designed to be inexpensive and easy to use.
What modification process did Breakey go through before finalizing his invention?
He made many modifications to his prototype.
Iteration is key in the design process.
List two key characteristics that Breakey’s paint roller design needed to have.
- Easy to use in large or small spaces
- Inexpensive to make
What are structures classified according to?
Structures can be interpreted and classified according to the materials and components they are made of
This classification helps in understanding both natural and human-built structures.
How can one analyze the characteristics of structures?
By matching natural structures with similar human-built structures and comparing their similarities and differences
Characteristics can include shape, function, materials, and mechanisms.
Fill in the blank: A bat’s wing and an airplane wing are similar in _______.
shape
This similarity allows both structures to fulfill the function of flight.
True or False: The materials used in a bat’s wing and an airplane wing are the same.
False
They differ significantly in materials, with bat wings made of biological tissues and airplane wings made of metal and composite materials.
What function do both bat’s wings and airplane wings serve?
Both provide a means to fly
This functional similarity is a key point in comparing natural and human-engineered structures.
What is one major difference between a bat’s wing and an airplane wing?
The materials they are made of
Bat wings are composed of organic materials, while airplane wings are typically constructed from metals and composites.
What does aesthetics refer to?
The pleasing appearance or effect that an object has because of its design.
Do all structures need to be aesthetically pleasing?
No, not all structures need to be aesthetically pleasing.
What is an example of a structure that does not need to be beautiful in design?
The framework supporting a train trestle.
What are the essential qualities that a train trestle framework must have?
Strong and stable.
What should a park band shell be like in terms of aesthetics?
Pleasing to look at and use.
Fill in the blank: Aesthetics refers to the _______ appearance or effect that an object has because of its design.
[pleasing]
What does aesthetics refer to?
The pleasing appearance or effect that an object has because of its design.
Do all structures need to be aesthetically pleasing?
No, not all structures need to be aesthetically pleasing.
What is an example of a structure that does not need to be beautiful in design?
The framework supporting a train trestle.
What are the essential qualities that a train trestle framework must have?
Strong and stable.
What should a park band shell be like in terms of aesthetics?
Pleasing to look at and use.
Fill in the blank: Aesthetics refers to the _______ appearance or effect that an object has because of its design.
[pleasing]
What are structures that provide protection and are portable?
Teepees, yurts, and tents
Examples include North American teepees, Siberian yurts, and tents from the Middle East.
What material was commonly used for houses built by early peoples in Europe?
Sod
Sod is made from clumps of earth and was also used by pioneers in the Prairies.
Why were sod houses popular among early peoples?
Easy to obtain and cost nothing
Sod provided a relatively protected enclosure that could be heated by fire.
Fill in the blank: Many people around the world built homes that provided protection and were _______.
portable
True or False: The structures built by different cultures are all the same.
False
Structures vary widely among different cultures and times.
What traditional materials are used for constructing houses in hot climates?
Sun-baked brick (adobe), clay, or mud
These materials help keep interiors cool under intense sun.
What is the purpose of the shell form in hot climate houses?
To create interiors that can be kept cool
The shell form typically has few windows or door openings.
What types of materials have been used for dwellings in warm, wet countries?
Grasses and bamboo
These materials have been used for hundreds of years.
Why are some homes in wet countries constructed high on stilts?
To raise the dwelling above wet ground
This helps protect the homes from flooding.
What two essential characteristics do effective structures share?
- They are all basically stable
- They all provide shelter for the people who live in them
These characteristics are crucial for the functionality of any dwelling.
True or False: Houses in hot climates are often built with many windows to allow for ventilation.
False
These houses typically have few windows or door openings.
Fill in the blank: Dwellings made of grasses and bamboo have been built for _______ in many warm, wet countries.
[hundreds of years]
What is a force?
A push or pull that tends to cause an object to change its movement or shape.
Does the size of a force have an effect on your ability to resist it? True or False?
True.
What should you do to avoid injury when testing the size of a force?
Do not overload your hands and allow time for your arms to recover.
What is being tested in Figure 2.2?
The effect of the direction of a force on your ability to resist it.
What should you do before testing the direction of a force?
Record your prediction.
What type of pressure should be applied during the experiment?
Gentle but firm pressure.
Fill in the blank: A force is a _____ that tends to cause an object to change its movement or shape.
[push or pull]
What is a force?
A push or pull that tends to cause an object to change its movement or shape.
Does the size of a force have an effect on your ability to resist it? True or False?
True.
What should you do to avoid injury when testing the size of a force?
Do not overload your hands and allow time for your arms to recover.
What is being tested in Figure 2.2?
The effect of the direction of a force on your ability to resist it.
What should you do before testing the direction of a force?
Record your prediction.
What type of pressure should be applied during the experiment?
Gentle but firm pressure.
Fill in the blank: A force is a _____ that tends to cause an object to change its movement or shape.
[push or pull]
What are the three factors that determine the effect of a force on a structure?
The magnitude of the force, the direction of the force, the location where the force is applied
These factors are critical in engineering and physics to predict how structures will respond to applied forces.
Define the term ‘magnitude’ in the context of forces.
The size of the force
Magnitude is a quantitative measure that affects how much a force will impact a structure.
True or False: The direction of a force does not affect its impact on a structure.
False
The direction of a force is one of the key factors that determine its effect on a structure.
Fill in the blank: The __________ where the force is applied is one of the three factors that influence the effect of that force on a structure.
location
The location of force application can significantly affect structural integrity and performance.
What are the three factors that determine the effect of a force on a structure?
The magnitude of the force, the direction of the force, and the location where the force is applied.
Fill in the blank: The actual effect of a force on a structure depends on its _______.
[magnitude, direction, and location]
True or False: The bigger a force’s magnitude, the weaker its effect on a structure.
False
What does the magnitude of a force refer to?
The size of the force.
What is meant by the direction of a force?
The orientation in which the force is applied.
What does the location refer to in the context of force application?
The specific point on the structure where the force is applied.
How does the magnitude of a force affect its strength?
The bigger the force’s magnitude, the stronger it is.
How are forces represented in drawings?
Forces are represented by arrows.
What does the direction of an arrow indicate in force representation?
The direction in which the force is acting.
What does the length or size of an arrow represent?
How strong the force is.
What happens to the effect of a force as its magnitude increases?
The stronger the force, the more effect it will have on a structure.
What factor influences the effect of a strong force on a structure?
The mass of the structure.
True or False: The effect of a force is solely determined by its magnitude.
False.
What determines the effect of a force on a structure aside from its magnitude?
The direction in which the force acts.
Fill in the blank: The bigger a force’s ______, the stronger it is.
magnitude.
What can be inferred when two forces have the same magnitude but different directions?
They may have different effects on the structure.
What is a key visual representation tool for understanding forces acting on structures?
Arrows in drawings.
What effect does the location of force application have on an object?
It affects the outcome, potentially causing the object to topple if applied too high.
True or False: Applying a force at a point high up on an object may cause it to slide without toppling.
False
Fill in the blank: The outcome of applying a force depends on the _______ at which it is applied.
[location]
What may happen when a force is applied too high up on an object?
It may cause the object to topple over.
In the context of pushing a fridge, which direction is more difficult?
Pushing it in one direction (A) compared to the other direction (B).
What effect does the location of force application have on an object?
It affects the outcome, potentially causing the object to topple if applied too high.
True or False: Applying a force at a point high up on an object may cause it to slide without toppling.
False
Fill in the blank: The outcome of applying a force depends on the _______ at which it is applied.
[location]
What may happen when a force is applied too high up on an object?
It may cause the object to topple over.
In the context of pushing a fridge, which direction is more difficult?
Pushing it in one direction (A) compared to the other direction (B).
What is the standard unit for measuring force?
The newton (N)
The newton is named after Sir Isaac Newton.
How much force is needed to hold up a mass of 100 g?
One newton
This is similar to the force required to hold an apple in your hand.
How much force is approximately needed to hold a 1-kg book?
About 10 N
This is a practical example of force measurement.
Who is the newton named after?
Sir Isaac Newton
He was an English scientist.
In what year did Sir Isaac Newton describe the ‘law of gravitation’?
1687
This was a significant contribution to physics.
Fill in the blank: One newton is the amount of force needed to hold up a mass of _______.
100 g
What role do mass and distance play in Newton’s law of gravitation?
They are key factors in the law
The law describes how gravitational force depends on the masses involved and the distance between them.
What is an external force?
A force that is applied on a structure by something else.
Give an example of an external force.
Walking into wind or standing in waves.
What must all structures on Earth be able to resist?
The force of gravity.
How does gravity act on objects on Earth?
It constantly pulls them towards the Earth.
What is mass?
The amount of matter in an object.
What is the relationship between mass and gravitational force?
The more mass an object has, the greater the gravitational force.
What do astronauts experience when the space shuttle orbits Earth?
Weightlessness.
Fill in the blank: Gravity is the pull of _______.
Earth.
True or False: Gravity is considered an external force.
True.
What is the point where we can think of the downward force of gravity acting on a structure?
Centre of gravity
The centre of gravity is an imaginary point that helps in analyzing the stability of structures.
What happens to your body when you stand on one foot due to gravity?
You might have to move your arms or lean to one side
This illustrates the effect of gravity on balance and stability.
How does the location of the centre of gravity affect a structure?
It determines the structure’s stability
A structure supported at its centre of gravity will remain balanced.
True or False: Gravity acts on all parts of a structure equally.
True
Gravity influences every part, but the centre of gravity is a singular point for analysis.
Fill in the blank: The _______ is where gravity acts on a structure.
centre of gravity
This concept is crucial for understanding stability in physical structures.
What is the point where we can think of the downward force of gravity acting on a structure?
Centre of gravity
The centre of gravity is an imaginary point that helps in analyzing the stability of structures.
What happens to your body when you stand on one foot due to gravity?
You might have to move your arms or lean to one side
This illustrates the effect of gravity on balance and stability.
How does the location of the centre of gravity affect a structure?
It determines the structure’s stability
A structure supported at its centre of gravity will remain balanced.
True or False: Gravity acts on all parts of a structure equally.
True
Gravity influences every part, but the centre of gravity is a singular point for analysis.
Fill in the blank: The _______ is where gravity acts on a structure.
centre of gravity
This concept is crucial for understanding stability in physical structures.
What is the main method of increasing a structure’s stability?
Increase the width of its base relative to its height
This can be achieved by placing most of the mass of the structure close to the ground.
What effect does lowering the centre of gravity have on a structure?
It increases stability
True or False: A structure with a low centre of gravity and wide base is typically stable.
True
Fill in the blank: The point on a ruler where it will balance is known as the _______.
centre of gravity
Which is generally more stable, a structure with a narrow base or a wide base?
Wide base
What is one way to increase stability in a structure?
Place most of the mass close to the ground
What is symmetry in the context of a balanced ruler?
A balanced arrangement of mass that occurs on opposite sides of a line or plane, or around a centre or axis.
Symmetry ensures equal force of gravity on both sides of the centre point.
What happens to the ruler if the finger is moved away from the centre?
The mass on one side becomes greater, leading to an unbalanced ruler.
This results in greater gravitational force on the side with more mass.
For a symmetrical structure to be stable, what must be true about its mass distribution?
The mass must be distributed equally around the centre of the structure’s base.
This ensures equal force of gravity around the centre.
True or False: A symmetrical arrangement guarantees stability.
True.
Stability is achieved when mass is evenly distributed.
Fill in the blank: The force of gravity on either side of the centre point is _______.
the same.
What is the definition of a load in structural engineering?
A load is an external force on a structure.
What must a bookcase be designed to support?
Its own weight and the weight of the books it holds.
What factors contribute to the load on a bridge?
The force of gravity on a car, the force of wind, and the weight of the materials that make up the bridge.
What are the two types of loads that can affect structures?
Static and dynamic loads.
What is a static load?
The weight of a structure and the non-moving load it supports.
True or False: A static load changes frequently over time.
False
Fill in the blank: The weight of the books in a bookcase is a ______ on the bookcase.
load
What does the term ‘static’ refer to in the context of loads?
Not moving or changing.
What is an example of a dynamic load?
The push of a force, such as the wind blowing on a tower.
How does gravity affect the load on structures?
It pulls down on the structure and its contents.
What happens if a bookcase is overloaded?
It may fail to support the weight of the books.
What is the force of gravity acting on the mass of the bookcase considered?
A load.
What is the definition of a load in structural engineering?
A load is an external force on a structure.
What must a bookcase be designed to support?
Its own weight and the weight of the books it holds.
What factors contribute to the load on a bridge?
The force of gravity on a car, the force of wind, and the weight of the materials that make up the bridge.
What are the two types of loads that can affect structures?
Static and dynamic loads.
What is a static load?
The weight of a structure and the non-moving load it supports.
True or False: A static load changes frequently over time.
False
Fill in the blank: The weight of the books in a bookcase is a ______ on the bookcase.
load
What does the term ‘static’ refer to in the context of loads?
Not moving or changing.
What is an example of a dynamic load?
The push of a force, such as the wind blowing on a tower.
How does gravity affect the load on structures?
It pulls down on the structure and its contents.
What happens if a bookcase is overloaded?
It may fail to support the weight of the books.
What is the force of gravity acting on the mass of the bookcase considered?
A load.
What are the two types of loads that can affect structures?
Static and dynamic loads
What is a static load?
The weight of a structure and the non-moving load it supports
What does static mean?
Not moving or changing
Give two examples of static loads.
- Wood, nails, and screws used to make a bookcase
- Steel beams, cables, rivets, and steel plates used to construct a bridge
What is a dynamic load?
Forces that change over time, such as wind or moving vehicles
True or False: The weight of a bridge is considered a dynamic load.
False
Fill in the blank: The _______ of wind is an example of a dynamic load.
[force]
What type of load is the weight of a truck classified as?
Dynamic load
What is an external force that acts on all parts of a structure?
Gravity
Gravity is the force that creates a static load, also known as dead load.
What is another term for static load?
Dead load
Static load refers to the constant weight acting on a structure.
What is a dynamic load?
An external force that moves or changes with time
Dynamic loads can change rapidly, such as in the case of strong winds or earthquakes.
Give an example of a dynamic load.
The weight of moving students on a staircase
This illustrates how dynamic loads can fluctuate based on movement.
What is another term for dynamic load?
Live load
Live load refers to loads that vary over time, unlike static loads.
What must designers plan for in structures?
Resistance to both dynamic loads and static loads
Effective structural design requires consideration of both types of loads.
What are the two conditions engineers use to decide the type of bridge to build?
- What the bridge is crossing (e.g., water or land)
- What kinds of loads the bridge will be supporting
These conditions help engineers determine the most suitable bridge design for specific situations.
What is the most common type of bridge used?
Beam bridge
The beam bridge is characterized by its simple structure and flat design.
Describe a simple beam bridge.
A simple beam bridge is flat and is supported at its two ends.
Longer beam bridges may require additional supports, known as piers.
True or False: A longer beam bridge is always supported at its two ends.
False
Longer beam bridges may also be supported by additional piers.
Fill in the blank: A beam bridge is supported at its _______.
two ends
This is a defining characteristic of a simple beam bridge.
What are the two conditions engineers use to decide the type of bridge to build?
- What the bridge is crossing (e.g., water or land)
- What kinds of loads the bridge will be supporting
These conditions help engineers determine the most suitable bridge design for specific situations.
What is the most common type of bridge used?
Beam bridge
The beam bridge is characterized by its simple structure and flat design.
Describe a simple beam bridge.
A simple beam bridge is flat and is supported at its two ends.
Longer beam bridges may require additional supports, known as piers.
True or False: A longer beam bridge is always supported at its two ends.
False
Longer beam bridges may also be supported by additional piers.
Fill in the blank: A beam bridge is supported at its _______.
two ends
This is a defining characteristic of a simple beam bridge.
What is a truss bridge?
A lightweight but strong bridge made of trusses along its sides.
Trusses are triangle-shaped frames that provide structural support.
What shape are the frames in a truss bridge?
Triangle-shaped.
Triangles are used because they are strong and stable shapes.
What is a simple suspension bridge?
A bridge that hangs between two ends and is supported by main cables anchored in concrete
Simple suspension bridges can also use natural supports like trees.
What are the main components of a modern suspension bridge?
Tall towers, main cables, smaller cables, and concrete anchors
The main cables hold up the bridge, while smaller cables support the roadway.
Which ancient civilizations first recognized the structural advantages of the arch?
The ancient Egyptians and Greeks
These civilizations understood the benefits of arch structures for stability.
Who made the arch a regular building feature in architecture?
The Romans
The Romans utilized arches extensively in their architectural designs.
Fill in the blank: The main cables of a suspension bridge are anchored in _______.
concrete
List the supporting elements of a suspension bridge.
- Tall towers
- Main cables
- Smaller cables
- Concrete anchors
True or False: A simple suspension bridge can be supported by trees.
True
What role do smaller cables play in a suspension bridge?
They support the roadway
Smaller cables are suspended from the main cables to hold up the bridge deck.
What is a simple suspension bridge?
A bridge that hangs between two ends and is supported by main cables anchored in concrete
Simple suspension bridges can also use natural supports like trees.
What are the main components of a modern suspension bridge?
Tall towers, main cables, smaller cables, and concrete anchors
The main cables hold up the bridge, while smaller cables support the roadway.
Which ancient civilizations first recognized the structural advantages of the arch?
The ancient Egyptians and Greeks
These civilizations understood the benefits of arch structures for stability.
Who made the arch a regular building feature in architecture?
The Romans
The Romans utilized arches extensively in their architectural designs.
Fill in the blank: The main cables of a suspension bridge are anchored in _______.
concrete
List the supporting elements of a suspension bridge.
- Tall towers
- Main cables
- Smaller cables
- Concrete anchors
True or False: A simple suspension bridge can be supported by trees.
True
What role do smaller cables play in a suspension bridge?
They support the roadway
Smaller cables are suspended from the main cables to hold up the bridge deck.
What is an arch bridge designed to withstand?
Heavy loads
The design allows it to handle dynamic loads from people and traffic.
How does the load in an arch bridge affect its structure?
Each piece of wood or stone pushes against the adjacent piece
This push is eventually transferred to the end supports.
What happens to the load transferred to the end supports of an arch bridge?
It is embedded in the ground, which pushes back
This resistance is passed back through all the pieces creating the arch.
What is the primary function of an aqueduct?
To carry a large quantity of flowing water between places
Aqueducts are a type of bridge specifically designed for water transport.
True or False: Many Roman aqueducts are still standing today.
True
This highlights the durability and engineering of ancient Roman structures.
What is an arch bridge designed to withstand?
Heavy loads
The design allows it to handle dynamic loads from people and traffic.
How does the load in an arch bridge affect its structure?
Each piece of wood or stone pushes against the adjacent piece
This push is eventually transferred to the end supports.
What happens to the load transferred to the end supports of an arch bridge?
It is embedded in the ground, which pushes back
This resistance is passed back through all the pieces creating the arch.
What is the primary function of an aqueduct?
To carry a large quantity of flowing water between places
Aqueducts are a type of bridge specifically designed for water transport.
True or False: Many Roman aqueducts are still standing today.
True
This highlights the durability and engineering of ancient Roman structures.
What are performance requirements in engineering?
Conditions that a structure must meet after it is built to show it is performing to certain standards
Performance requirements ensure safety, cost-effectiveness, and efficiency.
How is load performance typically expressed?
As a maximum weight
This indicates how much weight a structure can support safely.
What is an example of a performance requirement for a waterslide?
The structure must be able to support the weight of 200 people at one time, plus the weight of the water
This ensures that the waterslide can handle expected usage safely.
What must a structure withstand according to performance requirements?
High winds and heavy snows in winter without becoming unstable
This is crucial for structures in areas prone to extreme weather.
What other aspects do performance requirements apply to aside from load performance?
- Safety of the structure
- Effectiveness in meeting its intended purpose
Performance requirements encompass various functional and safety criteria.
What are performance requirements in engineering?
Conditions that a structure must meet after it is built to show it is performing to certain standards
Performance requirements ensure safety, cost-effectiveness, and efficiency.
How is load performance typically expressed?
As a maximum weight
This indicates how much weight a structure can support safely.
What is an example of a performance requirement for a waterslide?
The structure must be able to support the weight of 200 people at one time, plus the weight of the water
This ensures that the waterslide can handle expected usage safely.
What must a structure withstand according to performance requirements?
High winds and heavy snows in winter without becoming unstable
This is crucial for structures in areas prone to extreme weather.
What other aspects do performance requirements apply to aside from load performance?
- Safety of the structure
- Effectiveness in meeting its intended purpose
Performance requirements encompass various functional and safety criteria.
What happens when you crumple a piece of cellophane into a ball and put it on the table?
The cellophane slowly opens up again
This demonstrates the properties of materials and internal forces at work.
Why does an elastic band snap when holding a collection of cards together?
The internal forces within the elastic band exceed its elastic limit
This illustrates the concept of internal forces and material limits.
What is an internal force?
A force that one part of a structure exerts on other parts of the same structure
Internal forces act within a structure.
Why does wringing a towel work better than squeezing it to remove excess water?
Wringing applies a different type of internal force that is more effective
The mechanics of wringing involve twisting actions that enhance water removal.
Fill in the blank: Internal forces are forces that act ______ a structure.
within
True or False: Internal forces can be felt when pressing the palms of your hands together.
True
This illustrates the concept of internal forces exerted by muscles.
What happens when you crumple a piece of cellophane into a ball and put it on the table?
The cellophane slowly opens up again
This demonstrates the properties of materials and internal forces at work.
Why does an elastic band snap when holding a collection of cards together?
The internal forces within the elastic band exceed its elastic limit
This illustrates the concept of internal forces and material limits.
What is an internal force?
A force that one part of a structure exerts on other parts of the same structure
Internal forces act within a structure.
Why does wringing a towel work better than squeezing it to remove excess water?
Wringing applies a different type of internal force that is more effective
The mechanics of wringing involve twisting actions that enhance water removal.
Fill in the blank: Internal forces are forces that act ______ a structure.
within
True or False: Internal forces can be felt when pressing the palms of your hands together.
True
This illustrates the concept of internal forces exerted by muscles.
What is tension?
A force that acts to stretch and pull apart something
Tension can cause lengthening and possibly snapping of a component.
Name three structures that have components that must resist tension.
- Ski lifts
- Hydro towers
- Running shoes
These structures have parts designed to withstand the forces of tension.
How can tension be used advantageously?
Through cables used to hold up a suspension bridge
Cables are designed to withstand tension and provide structural support.
What is shear?
A force that acts to push parts that are in contact with each other in opposite directions
Shear can lead to deformation or failure of materials.
Identify three structures that must resist shear.
- Doors
- Airplanes
- Scissors
These structures experience shear forces during their operation.
What are complementary forces?
Different kinds of internal forces acting on a structure at the same time
Give an example of complementary forces.
Bending of a beam
What happens to a beam when it is bent into a U-shape?
Compression is produced on the top and tension on the bottom
What occurs if the load on a beam is too great?
The beam will break
What is the result of a beam’s failure to resist either compression or tension?
The beam breaks
How can engineers determine how to improve a beam’s structure?
By examining where a break happens on the beam
If a beam breaks first along the upper surface, what design change should be made?
Design the upper surface to be strong enough to resist compression
If a beam breaks first along the lower surface, what design change would you recommend?
Design the lower surface to be strong enough to resist tension
Fill in the blank: When a beam is bent, the top experiences _______ and the bottom experiences tension.
compression
True or False: A beam can withstand any load without breaking.
False
What is the strongest two-dimensional shape?
Triangle
A triangle is noted for its rigidity and strength compared to squares and rectangles.
What is the strongest three-dimensional shape?
Triangular prism
A triangular prism is stronger than rectangular prisms and other multi-sided shapes.
What happens to the shape of a square and rectangle under pressure?
They shift slightly
Unlike triangles, squares and rectangles can change shape under stress.
Why is a triangle considered a strong shape?
It cannot be bent easily
The rigidity of the triangle contributes to its strength.
Fill in the blank: A _______ is a very strong and rigid shape that cannot be bent easily.
triangle
What exercise can be used to demonstrate the strength of different shapes?
Using straws
The exercise involves comparing how different shapes respond to pressure.
True or False: A triangular prism is weaker than a rectangular prism.
False
A triangular prism is stronger than a rectangular prism.
In structural shapes, which is stronger: a triangular prism or a pentagonal prism?
Triangular prism
Triangular prisms are generally stronger than other multi-sided shapes.
What is the strongest two-dimensional shape?
Triangle
A triangle is noted for its rigidity and strength compared to squares and rectangles.
What is the strongest three-dimensional shape?
Triangular prism
A triangular prism is stronger than rectangular prisms and other multi-sided shapes.
What happens to the shape of a square and rectangle under pressure?
They shift slightly
Unlike triangles, squares and rectangles can change shape under stress.
Why is a triangle considered a strong shape?
It cannot be bent easily
The rigidity of the triangle contributes to its strength.
Fill in the blank: A _______ is a very strong and rigid shape that cannot be bent easily.
triangle
What exercise can be used to demonstrate the strength of different shapes?
Using straws
The exercise involves comparing how different shapes respond to pressure.
True or False: A triangular prism is weaker than a rectangular prism.
False
A triangular prism is stronger than a rectangular prism.
In structural shapes, which is stronger: a triangular prism or a pentagonal prism?
Triangular prism
Triangular prisms are generally stronger than other multi-sided shapes.
What is an arch in the context of structures?
A common shape in structures such as bridges that can support a large load by carrying the force down through the arch to the foundation.
Arches are designed to spread out the load effectively.
How does an arch support a load?
The force of the load is carried down through the arch to the foundation, spreading out the load.
This mechanism allows arches to bear significant weight.
What happens if a plank is weak when crossing a river?
It may bend, and there is a chance of getting wet if one bounces up and down on it.
This illustrates the importance of structural integrity.
True or False: An arch can only support small loads.
False
Arches are capable of supporting large loads.
Fill in the blank: An arch helps to _______ the load.
[spread out]
This is crucial for maintaining structural stability.
What is a simple beam?
A flat structure supported at each end.
What happens to a beam if too much weight is put on it in the middle?
It will bend in a U-shape and may even break.
How can the strength of a beam be increased?
By changing its shape.
What shape gives an I-beam its strength?
The I-shape.
What is the mass comparison between I-beams and solid beams?
I-beams have less mass than solid beams.
What are girders or box beams?
Long beams in the shape of hollow rectangular prisms.
Fill in the blank: A simple beam is supported at _______.
[each end]
True or False: Changing the shape of a beam can reduce its strength.
False
What is a simple beam?
A flat structure supported at each end.
What happens to a beam if too much weight is put on it in the middle?
It will bend in a U-shape and may even break.
How can the strength of a beam be increased?
By changing its shape.
What shape gives an I-beam its strength?
The I-shape.
What is the mass comparison between I-beams and solid beams?
I-beams have less mass than solid beams.
What are girders or box beams?
Long beams in the shape of hollow rectangular prisms.
Fill in the blank: A simple beam is supported at _______.
[each end]
True or False: Changing the shape of a beam can reduce its strength.
False
What is structural stress?
The weakening of a structure due to a combination of external and internal forces acting on it.
Structural stress can lead to fatigue or failure if not properly managed.
What is structural fatigue?
A permanent change in a structure caused by internal forces such as compression, tension, and shear.
This may result in cracks appearing in the material.
What is structural failure?
Occurs when a structure can no longer withstand the forces acting on it, leading to collapse or deformation.
Failure can manifest as buckling, shearing, or separating of components.
What are the two main properties a structure needs to avoid failure?
Strength and stiffness.
These properties help a structure resist stress and maintain integrity.
Define the strength of a structure.
The load at which it fails.
For example, if a skateboard collapses under 100 kg, its strength is 100 kg.
Define the stiffness of a structure.
Its ability to withstand changes in shape under a load.
A stiff structure prevents failure for loads up to its defined strength.
Fill in the blank: A structure needs _______ and stiffness to avoid failure.
strength
True or False: Structural failure can occur without any prior structural stress.
False.
Structural failure typically results from accumulated stress and fatigue.
What is structural stress?
The weakening of a structure due to a combination of external and internal forces acting on it.
Structural stress can lead to fatigue or failure if not properly managed.
What is structural fatigue?
A permanent change in a structure caused by internal forces such as compression, tension, and shear.
This may result in cracks appearing in the material.
What is structural failure?
Occurs when a structure can no longer withstand the forces acting on it, leading to collapse or deformation.
Failure can manifest as buckling, shearing, or separating of components.
What are the two main properties a structure needs to avoid failure?
Strength and stiffness.
These properties help a structure resist stress and maintain integrity.
Define the strength of a structure.
The load at which it fails.
For example, if a skateboard collapses under 100 kg, its strength is 100 kg.
Define the stiffness of a structure.
Its ability to withstand changes in shape under a load.
A stiff structure prevents failure for loads up to its defined strength.
Fill in the blank: A structure needs _______ and stiffness to avoid failure.
strength
True or False: Structural failure can occur without any prior structural stress.
False.
Structural failure typically results from accumulated stress and fatigue.
What property of a material refers to how easily it breaks?
Brittleness
Brittleness is a measure of a material’s tendency to fracture or break when subjected to stress.
What is the term for how easily a material can be made into wire?
Ductility
Ductility is an important property in materials used in electrical and structural applications.
What property measures a material’s resistance to indentation and scratching?
Hardness
Hardness is a critical factor in determining the wear resistance of materials.
How easy is it to shape a material referred to as?
Plasticity
Plasticity indicates a material’s ability to undergo significant deformation before rupture.
What property refers to a material’s ability to withstand high temperatures?
Resistance to heat
This property is crucial for materials used in high-temperature environments.
What property indicates how well a material can repel water?
Resistance to water
Water resistance is important for materials used in construction and outdoor applications.
What is the term for a material’s ability to withstand axial loads without collapsing?
Compression
Compression strength is vital for materials used in load-bearing applications.
What property measures a material’s ability to withstand being pulled apart?
Tensile strength
Tensile strength is essential for materials used in structural and mechanical engineering.
What is deformation in the context of structures?
Deformation is a change of shape in a structure or any structural component due to the material’s inability to resist the load acting on it.
Deformation can lead to failure of a component or the entire structure if excessive.
What property must materials have when designing a structure?
Materials must have enough strength to resist the forces acting on the structure and should not deform easily.
Strength is a critical factor in ensuring structural integrity.
True or False: Deformation can occur without any load acting on a structure.
False
Deformation occurs specifically because of the load acting on the material.
Fill in the blank: When too much deformation occurs, a component or the entire _______ might fail.
structure
This emphasizes the importance of controlling deformation in structural design.
What happens to the sides of an aluminum cantilever when a very small force is applied?
The sides start to return to their original shape once the force is removed.
This illustrates the elastic properties of materials.
What is deformation in the context of structures?
Deformation is a change of shape in a structure or any structural component due to the material’s inability to resist the load acting on it.
Deformation can lead to failure of a component or the entire structure if excessive.
What property must materials have when designing a structure?
Materials must have enough strength to resist the forces acting on the structure and should not deform easily.
Strength is a critical factor in ensuring structural integrity.
True or False: Deformation can occur without any load acting on a structure.
False
Deformation occurs specifically because of the load acting on the material.
Fill in the blank: When too much deformation occurs, a component or the entire _______ might fail.
structure
This emphasizes the importance of controlling deformation in structural design.
What happens to the sides of an aluminum cantilever when a very small force is applied?
The sides start to return to their original shape once the force is removed.
This illustrates the elastic properties of materials.
What is flexibility in materials?
Flexibility is the ability of a material to be bent under force without breaking
It indicates how much an object can change shape under a given load without breaking.
Why is flexibility important in tall buildings?
Tall buildings must resist the force of the wind, and being very strong and rigid is not necessarily the best design approach
Flexibility allows structures to withstand strong forces without sustaining damage.
How does a tall tree demonstrate flexibility?
A tall tree bends a little as the wind pushes against it and straightens up again when the wind stops
This ability to return to its original shape illustrates the concept of flexibility.
What have structural engineers learned from nature regarding flexibility?
Structural engineers have found ways to use materials and combine structural components to make buildings in high hazard wind or earthquake zones more flexible
This approach mimics the flexibility observed in trees.
Fill in the blank: Flexibility allows trees to resist being deformed under strong forces like _______.
wind
What is flexibility in materials?
Flexibility is the ability of a material to be bent under force without breaking
It indicates how much an object can change shape under a given load without breaking.
Why is flexibility important in tall buildings?
Tall buildings must resist the force of the wind, and being very strong and rigid is not necessarily the best design approach
Flexibility allows structures to withstand strong forces without sustaining damage.
How does a tall tree demonstrate flexibility?
A tall tree bends a little as the wind pushes against it and straightens up again when the wind stops
This ability to return to its original shape illustrates the concept of flexibility.
What have structural engineers learned from nature regarding flexibility?
Structural engineers have found ways to use materials and combine structural components to make buildings in high hazard wind or earthquake zones more flexible
This approach mimics the flexibility observed in trees.
Fill in the blank: Flexibility allows trees to resist being deformed under strong forces like _______.
wind
What are some common fasteners used to hold components together?
Nails, screws, rivets, tacks, staples
These fasteners utilize friction between the metal and surrounding material.
What is the primary mechanism by which nails, screws, rivets, tacks, and staples hold materials together?
Friction between the metal and the surrounding material
This mechanism is essential in modern construction.
What is one advantage of using screws, tacks, and staples in construction?
They can be easily removed to dismantle a structure
This feature is beneficial for temporary or adjustable constructions.
True or False: Riveted structures are common in modern construction for maximum strength.
True
Steel framing often utilizes rivets for enhanced durability.
Fill in the blank: Modern structures are usually made of steel framing ______ together for maximum strength.
riveted
This technique contributes to the structural integrity of buildings.
What materials are wood components often fastened with?
Nails and screws
These fasteners are preferred for joining wooden elements.
What are some common fasteners used to hold components together?
Nails, screws, rivets, tacks, staples
These fasteners utilize friction between the metal and surrounding material.
What is the primary mechanism by which nails, screws, rivets, tacks, and staples hold materials together?
Friction between the metal and the surrounding material
This mechanism is essential in modern construction.
What is one advantage of using screws, tacks, and staples in construction?
They can be easily removed to dismantle a structure
This feature is beneficial for temporary or adjustable constructions.
True or False: Riveted structures are common in modern construction for maximum strength.
True
Steel framing often utilizes rivets for enhanced durability.
Fill in the blank: Modern structures are usually made of steel framing ______ together for maximum strength.
riveted
This technique contributes to the structural integrity of buildings.
What materials are wood components often fastened with?
Nails and screws
These fasteners are preferred for joining wooden elements.
What is the purpose of notches cut into logs in construction?
To ensure that the parts in the structure will remain tightly interlocked
This technique is commonly used in furniture making for strong joints.
What is friction in the context of surfaces?
The force as two surfaces rub against one another.
How can the amount of friction be increased?
By increasing the area in contact.
What construction method allows wood to be joined together without screws or nails?
Interlocking pieces.
What is the purpose of notches cut into logs in construction?
To ensure that the parts in the structure will remain tightly interlocked
This technique is commonly used in furniture making for strong joints.
What is friction in the context of surfaces?
The force as two surfaces rub against one another.
How can the amount of friction be increased?
By increasing the area in contact.
What construction method allows wood to be joined together without screws or nails?
Interlocking pieces.
What is a method of joining that actually changes the two surfaces being connected?
Bonding
Bonding involves using a common material as a bonding substance between the surfaces.
Name three materials that can be used for bonding surfaces.
- Adhesive glue
- Tape
- Cement
- Welds
These materials create a bond between two surfaces when applied.
What type of tape is mentioned as a bonding material?
Tape with glue on one side
This type of tape adheres to surfaces to create a bond.
How do some types of glue create a bond?
By dissolving the surfaces
This process creates a chemical change that allows the surfaces to mix and harden together.
True or False: Welds only join materials without altering their surfaces.
False
Welds create a bond by melting the surfaces of the materials, thus changing them.
Fill in the blank: Adhesive glue, tape, cement, and _______ are examples of bonding materials.
welds
What happens to the surfaces when glue is applied?
They mix and harden into one solid mass
This occurs due to the chemical changes induced by the glue.
What are fixed joints?
Joints that are rigid to prevent any movement, created by methods like welding, cementing, gluing, or nailing
Fixed joints are used in structures where stability is critical.
What methods can create fixed joints?
- Welding
- Cementing
- Gluing
- Nailing
These methods are chosen based on material, usage, and location.
What are movable joints?
Joints that are flexible or mobile, allowing parts of the structure to move as required
Examples include hinges, pin joints, and human joints like knees and elbows.
Give examples of movable joints.
- Hinges
- Pin joints
- Flexible rubber tubing
- Knees
- Elbows
- Shoulders
Movable joints must withstand load and repeated movements.
Why might gluing not be appropriate for holding a fence together?
Gluing may not provide the required strength and durability for outdoor conditions
Certain applications require stronger, more permanent methods.
True or False: Movable joints do not need to withstand load.
False
Movable joints must still be able to withstand load and stress.
What influences the choice of joining methods in structures?
- Material of components
- How the structure is to be used
- Where it is to be located
These factors help determine the most effective joining method.
Fill in the blank: The ultimate strength and stability of a structure depend on the right _______ and method of joining being used.
[materials]
Selecting appropriate materials is crucial for structural integrity.
What is the importance of joint selection in structural design?
The selection of joints affects the movement, strength, and stability of the structure
Proper joint selection is essential for the intended function of the structure.
What are fixed joints?
Joints that are rigid to prevent any movement, created by methods like welding, cementing, gluing, or nailing
Fixed joints are used in structures where stability is critical.
What methods can create fixed joints?
- Welding
- Cementing
- Gluing
- Nailing
These methods are chosen based on material, usage, and location.
What are movable joints?
Joints that are flexible or mobile, allowing parts of the structure to move as required
Examples include hinges, pin joints, and human joints like knees and elbows.
Give examples of movable joints.
- Hinges
- Pin joints
- Flexible rubber tubing
- Knees
- Elbows
- Shoulders
Movable joints must withstand load and repeated movements.
Why might gluing not be appropriate for holding a fence together?
Gluing may not provide the required strength and durability for outdoor conditions
Certain applications require stronger, more permanent methods.
True or False: Movable joints do not need to withstand load.
False
Movable joints must still be able to withstand load and stress.
What influences the choice of joining methods in structures?
- Material of components
- How the structure is to be used
- Where it is to be located
These factors help determine the most effective joining method.
Fill in the blank: The ultimate strength and stability of a structure depend on the right _______ and method of joining being used.
[materials]
Selecting appropriate materials is crucial for structural integrity.
What is the importance of joint selection in structural design?
The selection of joints affects the movement, strength, and stability of the structure
Proper joint selection is essential for the intended function of the structure.
What is the primary function of bones in the human body?
To form a structural frame that supports and protects other parts of the body.
Bones are hard and rigid materials with special properties suited for their function.
What connects the thigh bone to the shin bone?
Ligaments.
Ligaments are strong, flexible connective tissues.
What is the role of cartilage at the ends of some bones?
To reduce friction and provide a smooth surface for movement.
Cartilage helps absorb shock when bones bump together.
True or False: Cartilage is a hard material found in the human body.
False.
Cartilage is flexible and reduces friction between bones.
Fill in the blank: _______ are bands of strong, flexible connective tissue that connect bones.
Ligaments.
What happens to cartilage when you fall off your bicycle?
It helps to absorb the shock of bones being bumped together.
This function helps protect the bones from injury.
What type of material are bones classified as in the human body?
Hard and rigid materials.
This structure is essential for support and protection.
How many muscles are in the human body?
656
What type of tissue are muscles made of?
Semi-solid fibrous tissue
What is the primary function of muscles?
Contracting (shortening) and relaxing
How are muscles attached to bones?
By tendons
What qualities do tendons share with ligaments?
Strong and flexible
What happens when a skeletal muscle contracts?
A bone moves
What is the function of heart muscle?
Contracts and pumps blood
What do digestive tract muscles do?
Contract and move food along
What type of joints allow movement in many directions?
Ball-and-socket joints
Which joints are found in the elbows and knees?
Hinge joints
What type of joints are in the spinal column?
Pivot joints
What type of joints are found in the wrists?
Gliding joints
What type of joints do not allow movement at all?
Immovable joints
Where are immovable joints found in the body?
Between the bones of the skull
Fill in the blank: Tendons hold muscles to _______.
bones
True or False: The heart muscle is a type of skeletal muscle.
False
What is the function of the skull in relation to immovable joints?
Protects the brain
What are the primary components that form a shell and frame structure in the human body?
Skin, bones, joints, and connective tissue
What are the key properties of skin?
Tough, flexible, waterproof
What is one of the main functions of skin?
Provides structural shelter
How does skin protect the body?
From harmful bacteria
What role does skin play in temperature regulation?
Through perspiration and shivering
What materials make up the structure of a tree trunk?
Several layers of different materials
What is the function of bark in a tree?
Protects the inner layers of the tree
Fill in the blank: Skin helps to _______ your body’s temperature.
regulate
True or False: Skin is only made of one type of material.
False
What does the structure of a tree trunk maintain?
Strength and stability
What does the term ‘margin of safety’ refer to in design?
The limits within which a structure’s safety performance is felt to be acceptable
It acknowledges that perfect safety is impossible.
How is the concept of margin of safety illustrated with vehicles?
Vehicles are designed to operate safely within speed limits but must also be safe at slightly higher speeds
Example: A margin of safety might be 30 km/h or 40 km/h above the common speed limit.
What factors are considered when determining tire pressures in relation to margin of safety?
Size of tire, vehicle load, and increased temperature due to use, weather, or speed
These factors help ensure tires function safely under various conditions.
What happens if tires are over-inflated for heavier loads?
The margin of safety has been decreased, increasing the risk of a blow-out
Over-inflation can lead to reduced performance and safety.
How are building components designed with margin of safety in mind?
They must withstand three or four times their maximum intended load
This principle is crucial for ensuring structural integrity.
True or False: Designers aim for perfect safety in all structures.
False
It is acknowledged that perfect safety is impossible.
Fill in the blank: The margin of safety in vehicle design allows for operation at speeds _______.
slightly higher than the speed limit
This ensures vehicles remain safe even when driven above standard limits.
What does the term ‘margin of safety’ refer to in design?
The limits within which a structure’s safety performance is felt to be acceptable
It acknowledges that perfect safety is impossible.
How is the concept of margin of safety illustrated with vehicles?
Vehicles are designed to operate safely within speed limits but must also be safe at slightly higher speeds
Example: A margin of safety might be 30 km/h or 40 km/h above the common speed limit.
What factors are considered when determining tire pressures in relation to margin of safety?
Size of tire, vehicle load, and increased temperature due to use, weather, or speed
These factors help ensure tires function safely under various conditions.
What happens if tires are over-inflated for heavier loads?
The margin of safety has been decreased, increasing the risk of a blow-out
Over-inflation can lead to reduced performance and safety.
How are building components designed with margin of safety in mind?
They must withstand three or four times their maximum intended load
This principle is crucial for ensuring structural integrity.
True or False: Designers aim for perfect safety in all structures.
False
It is acknowledged that perfect safety is impossible.
Fill in the blank: The margin of safety in vehicle design allows for operation at speeds _______.
slightly higher than the speed limit
This ensures vehicles remain safe even when driven above standard limits.
What is the purpose of a divider when packing two layers of small glasses in a box?
To resist bending under the load of the top layer of glasses and to keep the glasses upright.
The divider must be both strong and smooth.
What shapes are considered strong for creating a support structure?
Triangles and arches.
These shapes provide stability and strength.
What is the problem with using a folded piece of paper as a divider?
The folded surface would cause the top glasses to fall over.
Stability of the glasses is compromised.
What is the solution to the packing problem described?
Combine a folded piece of paper with two smooth ones to create a sturdy divider.
This creates a strong interior and a smooth exterior.
Define corrugation.
The process of forming a material into wave-like ridges or folds.
Common examples include corrugated cardboard and corrugated metal.
What is lamination in the context of materials?
Laminating layers of a material together to create a strong bond.
This process enhances the strength of the material.
Fill in the blank: The result of combining a folded piece of paper with two smooth ones is a _______.
sturdy divider.
True or False: Corrugated cardboard is an example of a material that has undergone corrugation.
True.
What is the main benefit of using a corrugated structure in packing?
Increased strength and support for the items being packed.
This helps prevent damage during transport.
What is compression?
The process of reducing the size of an object by applying pressure
Compression often results in the creation of ridges or folds.
What are common examples of compression?
- Corrugated cardboard
- Corrugated metal
These materials are designed to withstand compressive forces.
What is lamination?
Gluing layers of a material together to create a strong bond
Laminated materials are stronger than a single piece of the same material of the same thickness.
How does lamination improve strength?
By overlapping, interlocking, and gluing members into single beams
This method is often used in laminated beams made of short pieces of wood.
What is plywood an example of?
A laminated material
Plywood typically consists of five or seven layers.
What is a common use of laminated materials in kitchen countertops?
A waterproof layer laminated onto wood
This enhances durability and resistance to moisture.
What is automobile safety glass made of?
Two pieces of glass with a layer of plastic in the middle
This design holds broken pieces of glass together upon impact.
What is the purpose of strengthening component arrangements?
To build stronger components when stronger materials are unavailable or unaffordable
This can involve using different arrangements such as arches for added strength.
True or False: Laminated materials can be made from a single piece of material.
False
Laminated materials are created by bonding multiple layers together.
