TECNHOLOGY STUDY NOTES
focusing on structures, mechanical systems, and electrical systems.
Technology Term 2 Study Notes Grade 8
1. Structures
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Definition: A structure is something built or constructed to support loads.
Types of Structures:
o Natural Structures: Made by nature (e.g., trees, spider webs).
o Man-Made Structures: Made by humans (e.g., buildings, bridges).
Forces on Structures:
o Tension: Pulling force.
o Compression: Pushing force.
o Shear: Sliding force.
o Torsion: Twisting force.
o Bending: Force causing bending.
Components of Structures:
o Beams: Horizontal structural members.
o Columns: Vertical structural members.
o Trusses: Frameworks of beams that create a rigid structure.
o Braces: Provide support to beams and columns.
2. Mechanical Systems
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Definition: Systems that use mechanical parts to perform a function.
Simple Machines: Basic mechanical devices that change the direction or magnitude
of a force.
o Lever: A rigid bar that rotates around a fulcrum to lift or move loads.
▪ Types of Levers:
• First-class (e.g., seesaw)
• Second-class (e.g., wheelbarrow)
• Third-class (e.g., fishing rod)
o Wheel and Axle: A larger wheel attached to a smaller axle so that these
rotate together.
o Pulley: A wheel with a groove for a rope that changes the direction of the
force.
o Inclined Plane: A flat surface tilted at an angle to help lift objects.
o Screw: An inclined plane wrapped around a cylinder.
o Wedge: Two inclined planes joined back-t s level, focusing on structures,
mechanical systems, and electrical systems
Summary of structures
Definition:
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Structure: An assembly of parts joined together to support loads and provide
stability.
Types of Structures:
1. Natural Structures: Formed by nature (e.g., trees, bones, spider webs).
2. Man-Made Structures: Created by humans (e.g., buildings, bridges, dams).
Forces Acting on Structures:
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Tension: A force that pulls or stretches material.
Compression: A force that squeezes material together.
Shear: A force that causes parts of a material to slide past one another.
Torsion: A twisting force.
Bending: A force that causes a material to bend.
Components of Structures:
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Beams: Horizontal members that support loads.
Columns: Vertical members that support beams and loads above them.
Trusses: Frameworks of beams arranged in triangles to provide stability and
support.
Braces: Diagonal members that help to stabilize beams and columns.
Structural Design:
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Materials Used:
o Wood: Lightweight and easy to work with, commonly used in residential
structures.
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o Steel: Strong and flexible, used in skyscrapers and bridges.
o Concrete: Durable and strong in compression, used in buildings and
foundations.
o Composite Materials: Combine two or more materials to leverage their
strengths.
Design Principles:
o Stability: Ensuring the structure can withstand applied forces without
collapsing.
o Strength: Using materials and designs that can bear the loads.
o Rigidity: Preventing excessive deformation under low....
Truss structures
Kingpost – under tension (supports the beam; keeps
rafters up)
Queen post –under tension (supports the rafters)
Strut –under compression (supports any member attached
to it)
Tie beam-under tension (hold the rafters in place)
Rafters-under compression (supports roof materials)
Tie- under tension (holds other members in place)
Gears
There are three types of gears in this
topic.
 The idler gear –is a gear placed between the drier gear
and the driven gear.
 Bevel gears-have teeth in a shape of a cone
 Drawing gear-have teeth as a time-consuming task
Types of materials and their impact on
the environment
Synthetic materials
Something made from artificial materials
Bio gradable
It is the ability to break down (decompose)
Non-Bio gradable
Any materials that cannot be broken down (decomposed)