TOPICS 1-4 REVIEW

1. TOPICS 1-4 REVIEW UNIT 4: STRUCTURES AND FORCES

2. TOPIC 1: TYPES OF STRUCTURES • ALL STRUCTURES ARE EITHER NATURAL OR MANUFACTURED • TYPES OF STRUCTURES: • MASS STRUCTURES • FRAME STRUCTURES • SHELL STRUCTURES • MIXTURE (FOOTBALL HELMET)

3. WHAT TYPE OF STRUCTURE AM I? • BACKPACKING TENT • POP CAN • CONCRETE BARRIER IN A PARKING LOT • HOUSE • SEASHELL • TURTLE’S SHELL • CLAY POT • BICYCLE • SKELETON

4. Topic 2: Describing Structures • Six categories: “For All Students Must Jump Far” • Function • Aesthetics • Materials • Joints • Fasteners

5. function • What it is used for. Describes what the structure is supposed to do. For example, the function of a bridge is to transport trains across a particular area. • Words to describe function: • Containing • Transporting • Sheltering • Supporting • Lifting • Fastening • Separating • Communicating • Breaking • Holding

6. aesthetics • Aesthetics definition: the study of beauty in art and nature • Think of the types of material used, or the colors a material might be painted. • Marble columns, clothing designs, arched doorways, etc. • Interesting textures, repeating patterns • Carefully chosen materials and design to make a structure look good • Think about it, a product that looks good on the shelf is more likely to sell right?

7. safety • MARGIN OF ERROR: EXTRA STRENGTH THAT ALLOWS A STRUCTURE TO WITH STAND MUCH LARGER LOADS THAN IT WOULD NORMALLY NEED TO CARRY. • BALANCING SAFETY WITH COST: GOOD DESIGN IS A CAREFUL BALANCE BETWEEN HAVING A GOOD MARGIN OF SAFETY AND REASONABLE COST.

8. MATERIALS • What is the structure made out of? • Cement, Steel, Wood, etc. • COMPOSITE MATERIALS: made from more than one kind of material. • Example: reinforced concrete—steel bars inside to help support • Example: Fiberglass cloth embedded in rigid plastic is molded into boat hulls • LAYERED MATERIALS: thin sheets or layers of materials, usually pressed or glued together. • Example: safety glass of a car window helps prevent shattering when glass breaks. • Example: tissue paper contains multiple layers of very thin paper. • LAMINATE: LAYERS OF DIFFERENT MATERIALS

9. CHOOSING MATERIALS • WHEN DESIGNERS ARE DECIDING WHICH TYPE OF MATERIALS TO USE IN THEIR STRUCTURE, THEY WILL CONSIDER THE FOLLOWING: • COST • APPEARANCE • ENVIRONMENTAL IMPACT • ENERGY EFFICIENCY

10. JOINTS • --ALL JOINTS ARE EITHER RIGID OR MOBILE • RIGID=DO NOT ALLOW MOVEMENT • MOBILE=ALLOWS MOVEMENT • SOME OTHER TYPES OF JOINTS ARE: • FASTENERS • INTERLOCKING SHAPES • TIES • ADHESIVES • MELTING

11. Types of joints: 1-fasteners • nails, bolts, screws, rivets, dowels --downside to fasteners is that they weaken material as they must poke

12. Types of joints: 2-interlocking shapes Clothing hem, paving stones, sheet metal, woodworking, dental fillings, etc. TYPES OF SEAMS: • DOVETAIL JOINT

13. Types of joints: 3-ties EXAMPLE OF TIES: thread, string, rope that fasten things together; example-clothing seam, shoelace, jacket hood.

14. TYPES OF JOINTS: 4-ADHESIVES ADHESIVES: sticky substances that hold things together. Thermosetting=heat Solvent-based=air dry THERMOSETTING SOLVENT-BASED

15. TYPES OF JOINTS: 5-MELTING • MELTING: Turn structures material into liquid and join with another piece. • Must be carefully cleaned • Must cool properly

16. TOPIC 3: MASS AND FORCES • YOUTUBE VIDEO “EUREKA!” • TERMS TO KNOW: • Mass: the amount of matter (stuff) an object has in it. NEVER CHANGES • Weight: a force that is caused by the gravitational pull between one object and another object. CAN CHANGE • HOW DOES AN OBJECT’S WEIGHT CHANGE? • CAN CHANGE WHEN THE OBJECT’S LOCATION CHANGES TO A PLACE WHERE THERE ISN’T AS MUCH GRAVITATIONAL PULL, FOR EXAMPLE, IN SPACE. • Newton: SI unit of force • 1 Newton=enough force to stretch a rubber-band • 10 N=enough force to lift a carton of milk • 200 N=the force of a hard-thrown baseball hitting your hand

17. Mass and force: • When converting: • Kilograms to Newtons=multiply by 10 • Grams to Kilograms=multiply by 1,000 • Grams to Newtons=divide by 100 • Newtons to Grams=multiply by 100 1 Kilogram=10 Newtons 1 Newton=100 Grams 1 Kilogram=1,000 Grams 1 Gram=0.01 Newtons

18. Topic 3 terms to know continued: • Forces: stresses such as pushes and pulls • Kilogram: same amount of mass as 1,000 grams • Milligram: 1000 miligrams=1 gram • Balance: type of measuring instrument used to determine an object’s mass

19. Topic 4: forces, loads, and stresses • Types of force: • -Shear force • -Torsion force • -Tension force • -Compression force

20. Tension force • Stretcha material by pulling ends apart. • -Tensile strength: largest tension force the material can stand before breaking.

21. Compression force • -ability to withstand crushing or squeezing together • Compressive strength: measures largest compression force the material can stand before losing its shape or breaking into pieces.

22. Shear force • -Bend or tear a material by pressing different parts in opposite directions at the same time. • *Shear strength: measures the largest shear force material can stand before ripping apart.

23. Torsion force: • Twist a material by turning ends in opposite directions. • *Torsion strength: measures the largest torsion force the material can stand and still spring back to its original shape.

24. Topic 4 additional terms: • Dead load: permanent force acting on a structure. Includes weight of actual structure. • Live load: a changing, non-permanent force acting on a structure. • External forces: forces acting on structure from outside • Internal forces: forces acting on structure from within the materials of structure, which can cause structure to change shape or size. • Deformation: change internally of structure’s shape or size.

25. Topic 4: resisting stress • -Steel: high tensile strength, strong force pulling particles together • -Graphite: low shear strength, particles arranged in layers, which is why its used for led pencils. • -Rubber: high torsion strength, particles attract each other in all directions; which is why they hold together when twisted.

26. Review: • What is the name for something that serves a specific function and resists forces? • building • design • load • structure STRUCTURE

27. REVIEW • A person's weight is really a measure of the gravitational force between that person and Earth. • True • False TRUE!

28. REVIEW: • Rigid joints are used in a structure to allow joined materials to move easily. • True • False FALSE!

29. REVIEW • What are the four types of structures? 1-Frame 2-Shell 3-Mass 4-Mixed

30. REVIEW • The Patterson family hired the Quick Fix Renovation Company to do some renovations in their home. They wanted doors placed into some walls and other walls removed in order to make the house more functional for their needs. Several weeks after the renovations were completed, Mrs. Patterson noticed that the ceiling was cracking and sagging where a wall had been removed. What is the most likely explanation for the sagging? • A. Cheap materials were used. • B. The removed wall helped to support the weight of the roof. • C. The removed wall originally divided two rooms. • D. The removed wall was poorly constructed. ANSWER: B

31. REVIEW • Which of the following is a composite material? • A. corrugated cardboard • B. wool • C. reinforced concrete • D. steel beams C. Reinforced Concrete

32. REVIEW: • Lucy, an architect with a Calgary firm, is responsible for designing a new public library. She has been told what the function will be and she knows the safety regulations. As well as function and safety, she wants the building to be beautiful. What is another word for "looking good" in structure design? • A. balanced • B. composition • C. symmetry • D. aesthetics D. Aesthetics

33. REVIEW • What is the name for the process of melting two pieces of the same material together? • A. welding • B. soldering • C. adhering • D. brazing A. Welding

34. REVIEW • What is the correct unit of measurement for weight? • pound • gram • kilogram • newton GRAM

35. REVIEW • Spider silk has a great deal of what type of strength? • Tensile (tension) • compressive • shear • torsion TENSION!