Bensyn Science Quiz Notes PDF

NOTES Topic 1: Types of Structures Definition of Structures: Structures are things that have a definite shape and size, which serve a definite function or purpose. To perform its function, every part of the structure must support forces (stresses such as pushes or pulls) that could damage its shape o...

NOTES Topic 1: Types of Structures Definition of Structures: Structures are things that have a definite shape and size, which serve a definite function or purpose. To perform its function, every part of the structure must support forces (stresses such as pushes or pulls) that could damage its shape or stability. Classifying Structures Natural Structures: Occur naturally in the environment. Manufactured Structures: Many are modeled after natural structures. Design: The shape and size of a structure and the materials of which it is composed. Three Types of Designs: 1. Mass Structure o Made by piling, stacking, or forming similar materials into a particular shape or design. o Advantages: Held in place by its own weight; losing small parts often has little effect on overall strength. 2. Frame Structure o A skeleton of strong materials, covered or filled with other materials.  Load-Bearing Walls: Support the weight of the structure.  Partition Walls: Divide spaces and do not bear loads. o Most common construction choice. 3. Shell Structure o Use thin, carefully shaped outer layers to provide strength and rigidity. o Features: 1. Encloses and supports. 2. Distributes forces evenly. o Problems: Weakness or imperfections in the covering can cause failure. Topic 2: Describing Structures Areas to Consider: 1. Function: What is the structure supposed to do? 2. Aesthetics: How it looks. 3. Safety: Margin of safety. 4. Material Properties: Characteristics must match the purpose. 5. Construction: How the structure is put together. Function: Examples include: Supporting a load. Enclosing a space. Transporting materials or people. The primary function is the most important and should always be met. Most structures must meet specific standards that are measurable. Aesthetics: Achieved through shape, texture, color, symmetry, and simplicity of patterns. Safety: Structures must be reliable and perform as expected over time to protect people’s safety and health. Materials: Properties: Each material has unique strengths and limitations. Composite Materials: Combine materials with different properties. o Example: Layers (e.g., plywood) glued together for combined properties. o Woven or Knit Materials: Interlacing fibers for added strength. Choosing Materials: 1. Cost: Can inexpensive materials perform over time? 2. Aesthetics: Will it remain appealing? 3. Environmental Impact: Does it harm the environment? 4. Energy Efficiency: Does it conserve energy? Joints:  Mobile Joints: Allow movement and must be lubricated. Rigid Joints: Examples include fasteners, ties, interlocking shapes, adhesives, and melted joints. o Fasteners: Nails, staples, bolts, screws, rivets, and dowels. o Interlocking Shapes: Fit together due to their shape. o Adhesives: Can fail under extreme conditions. o Melting: Welding and soldering fuse materials together. Topic 3: Mass and Forces Mass: Mass is the number of particles in a substance. Measured in kilograms (kg) or grams (g). Balance: A balance compares the mass of an object to a known standard. Forces and Weight: Force Unit: Newton (N). Force Meter: Measures the pull of gravity on a mass. Weight: The gravitational force between two objects depends on their masses and the distance between them. Mass is the amount of matter in an object. Weight is the gravitational force on an object. Topic 4: Forces, Loads, and Stresses External Forces: Static Load: Permanent force acting on a structure. Dynamic Load: Changing, non-permanent force. Impact Forces: Collisions with the structure. Internal Forces: Tension: Pulling apart. Compression: Pushing together.  Shear: Sliding forces. Torsion: Twisting forces. Bending: Combination of tension and compression. Resisting Stress: Material strength depends on particle attraction and direction of forces. Examples: Steel: Strong particle attraction. Graphite: Weak particle bonds. Rubber: Flexible bonds. Topic 5: How Structures Fail Material Failures: Shear: Particles separate, causing cracks. Bend/Buckle: Compression causes deformation. Torsion: Twisting damages structure integrity. Metal Fatigue: Repeated stress causes cracks. Preventative Reinforcements: Add triangles or cross-bracing for strength. Use I-beams, L-beams, or corrugated shapes. Topic 6: Designing with Forces Key Methods: 1. Distribute the Load: Spread forces across the structure. 2. Direct Forces: Control the path of forces. 3. Shape Strength: Design to withstand forces. Structural Problems and Solutions: Braces: Add strength by forming rigid triangles. Cantilever: Horizontal supports anchored at one end. Arches: Use a central keystone for strength.  Beams: Use cylindrical or hollow beams for efficiency. Using Friction: Friction helps stabilize structures and resist sliding. Topic 7: Stable Structures Stability Factors: Balance forces to prevent collapse. Locate center of gravity to ensure stability. o If the center of gravity shifts outside the base, the structure becomes unstable. Firm Foundations: Built on stable ground or solid bedrock. Use pilings or packed layers to distribute the load. Spread load over a larger area. Spin Stabilization: Rotational speed can improve stability for some structures (e.g., satellites). TEST REVIEW Topic 1: Types of Structures Definition of Structures: Structures are things that have a definite shape and size, which serve a definite function or purpose. To perform its function, every part of the structure must support forces (stresses such as pushes or pulls) that could damage its shape or stability. Classifying Structures Natural Structures: Occur naturally in the environment. Manufactured Structures: Many are modeled after natural structures. Design: The shape and size of a structure and the materials of which it is composed. Three Types of Designs: 1. Mass Structure  o Made by piling, stacking, or forming similar materials into a particular shape or design. o Advantages: Held in place by its own weight; losing small parts often has little effect on overall strength. 2. Frame Structure o Have a skeleton of strong materials filled or covered with other materials. o Load-Bearing Walls: Support the structure. o Partition Walls: Divide spaces. 3. Shell Structure o Structures that enclose and protect without a frame or solid mass inside. o Use a thin, shaped outer layer for strength. o Advantages: Spread forces throughout the structure for strength. o Disadvantages: Tiny weaknesses can cause failure. Topic 2: Describing Structures Areas to Consider: 1. Function: What the structure is supposed to do. 2. Aesthetics: How it looks (shape, texture, color, symmetry). 3. Safety: Margin of safety to ensure reliability. 4. Materials: Must match the structure's purpose. 5. Construction: How the structure is fastened or put together. Margin of Safety: Structures must be built to perform as expected for a long time, keeping people safe. Types of Joints: Mobile Joints: Allow movement (e.g., hinges, lubricated joints). Rigid Joints: Fixed connections (e.g., fasteners, ties, adhesives, welding). Topic 3: Mass and Weight Mass: The amount of matter in an object (measured in kilograms, kg). Weight: The force of gravity acting on an object's mass (measured in newtons, N). Difference: Mass is constant and does not change with location. Weight depends on gravity and changes with location. Topic 4: Forces, Loads, and Stresses External Forces: 1. Dead Load: Permanent forces acting on a structure. 2. Live Load: Non-permanent forces that change. 3. Impact Force: Forces from collisions. Internal Forces: 1. Tension: Pulling force. 2. Compression: Pushing force. 3. Torsion: Twisting force. 4. Shear: Sliding force. 5. Bending: Combination of tension and compression. Resisting Stress: Tensile Strength: Resistance to tension. Compressive Strength: Resistance to compression. Shear Strength: Resistance to shear forces. Topic 5: How Structures Fail Material Failure: Shear Failure: Particles slide apart. Bending/Buckling: Compression causes deformation. Torsion Failure: Twisting causes breaking or loss of shape. Metal Fatigue: Repeated stress causes cracks over time. Making Use of Stress: Reinforcements like braces or trusses can strengthen structures. Topic 6: Designing with Forces Three Key Methods: 1. Distribute the Load: Spread forces evenly. 2. Direct Forces Along Angled Components: Use shapes like triangles. 3. Shape Parts to Withstand Forces: Design materials to handle specific stresses. Structural Problems and Solutions: Problem 1: Frame structures can be pushed or pulled out of shape. o Solution: Use braces to form rigid triangles. Problem 2: Horizontal forces can cause bending. o Solution: Use cylindrical or I-beam shapes. Problem 3: Weak foundations lead to instability. o Solution: Use solid layers or pilings. Using Frictional Forces: Friction helps hold structures in place, especially against wind or other external forces. Topic 7: Stable Structures 5 Principles of Stability: 1. Center of Gravity: Balance the structure around a central point. 2. Thrust Line: Ensure forces stay within the base of the structure. 3. Symmetry: Evenly distribute mass. 4. Firm Foundation: Build on stable ground. 5. Balanced Forces: Counteract external forces for stability. Rapid Rotation: Spinning objects maintain stability through centripetal forces.