Properties of wood:
- DENSITY: this is an excellent indicator of wood strength. Density refers to how thick a piece of wood is; the thicker it is the stronger it will be.
- THERMAL PROPERTIES/TEMPERATURE EFFECT: Although wood is an excellent heat insulator, its strength and other properties are affected adversely by exposure for extended periods to temperatures above about 37°
- ENVIRONMENTALLY FRIENDLY: Timber is the most environmentally responsible building material. Timber has low production energy requirements and is a net carbon absorber. Timber is a renewable resource. Well-managed forests produce timber on a sustained continuous basis, with minimal adverse effects on soil and water values.
- STRONG AND LIGHTWEIGHT: Timber is strong, light and reliable making timber construction simpler and safer than steel or concrete construction.
- SAFE: Timber has low toxicity and therefore requires no special safety precautions to work with it, other than normal protection from dusts and splinters.
- EASY TO INSTALL: Timber is one of the easiest engineering materials to install.
- AFFORDABLE: comparatively, timber is cheaper that metal or concrete for construction.
Properties of Metals:
- Density: this refers to the weight of the metal or its specific gravity
- Fusibility: this is the ability of a metal to be melted when heated until it becomes liquid
- Magnetism: the property of a metal which enables it attract iron
- Ductility: this is ability of a metal to be drawn out r stretched without breaking
- Conductivity of Heat: ability of a metal to transfer heat generated from one end to the other.
- Fusibility: the ability of a metal to be melted when heated until they become liquid
- Tenacity: the ability of a metal to withstand stress
- Sound Test: the ability of a metal to give sound when struck
- Colour or Lustre: the ability of a metal to have a polished surface
- Toughness: the ability of a metal to resist bending
Properties of ceramics:
- They can break easily;
- They can withstand high temperature;
- Ceramics are less dense than most metals;
- They can be easily decorated;
- They are good electric insulators;
- They can withstand heavy compressive loads;
- They are not affected acids, water or oxygen.
Properties of Glass:
- Absorbs heat: Glass absorbs and transmits heat which means that if you heat a glass then the temperature of the contents inside of it will react.
- Glasses are light in weight
- They have good thermal and electrical resistance
- Durability: Glass is durable due to the strong bonds between the molecules in it. Its strength and its durability mainly depend on its thickness.
- Glass is static: Glass does not react with other materials and will not be a reactive to other materials and will not be decomposed by most acids.
- Transparency: Glass is a transparent substance which means you see through it.
Questions:
- Mention 4 professions that can be carried out in a workshop.
- Why should workshop users use goggles when carrying out some specific tasks in the workshop?
- List 5 workshop safety precautions.
- As related to metal, differentiate between ductility and fusibility.
- Describe how metal is a conductor of heat.
- At what temperature does an average wood lose its ability to withstand heat?
- Outline three important properties of glass.
- Between glass and ceramic, which is more commonly used as a good electrical insulator?
- Why is glass a durable material?
- What term refers to the ability of a material to withstand stress?
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