1. Exploration of Materials Properties: Every material has its own properties. When choosing materials for our design work, we must first analyze and compare their strength and weaknesses.

2. 1. Strength : It is the ability of material to resist a force without breaking or being permanently deformed. Different kinds of strength are given below: Exploration of Materials

3. a)Compressive Strength The ability to resist being crushed is called compress strength. For example, the material for the body of a car must possess high compressive strength. Exploration of Materials

4. b) Tensile Strength The ability to resist being stretched or pulled apart is called tensile strength. For example, the fishing rod must possess high tensile strength. Exploration of Materials

5. c)Bending Strength The ability to resist being bent is called bending strength. For example, a diving board must possess high bending strength. Exploration of Materials

6. d) Shear Strength The ability to resist pressing force acting from both sides of a point is called shear strength. For example, the beams of a bridge must have high shear strength. Exploration of Materials

7. 2. Toughness: This is the ability to resist cracking or breaking under load. For example, concrete is tough while glass is brittle( 易碎 ). Exploration of Materials

8. 3. Elasticity: It is ability to return to the original shape after having been deformed. For example, both rubber bands and Balsa wood have high elasticity. Exploration of Materials

9. 4. Hardness It is the ability to resist scratching( 刮 削 ), cutting or wearing( 磨耗 ). For example, cutting tools must be made of hard materials such as high speed steel( 鋒鋼 ) or high carbon steel( 高碳鋼 ). Exploration of Materials

10. 5.Durability: It is the ability to withstand weathering ( 風化 ) or corrosion( 腐蝕 ). For example, PVC pipes are more durable than cast iron pipes in drain construction. Exploration of Materials

11. 6. Malleability It is the ability to be rolled to a new shape without breaking. For example, aluminium is a malleable metal which can be folded and pressed to form different shapes. Exploration of Materials

12. 7. Others: There are other physical properties of materials which we have to consider in our design work. They are heat conductivity, electrical conductivity, fusibility ( 溶度 ), etc. Exploration of Materials