What are the characteristics of wood in the second grade science

The characteristics of wood are:

1. Naturalness: Wood is a natural material, and only it is directly taken from nature among the four main materials of steel, wood, cement and plastic, so wood has a production cost.

Low energy consumption, non-toxic, non-polluting and other characteristics.

2. Good texture: wood has good tactile properties that are easy to accept, far better than materials such as metal and glass.

3. Thermal insulation: the thermal conductivity of wood.

It is small, 2,000 times more thermally conductive than aluminum, and 30 times more thermally conductive than plastic. As a result, wood has good thermal insulation properties. Wood can be tempered and dehumidified, and has good environmental properties.

4. High strength-to-weight ratio: The ratio of some strength to weight of wood is higher than that of general metals, and it is a light and high-strength material.

5. Thermal insulation: The thermal conductivity of wood is very small, compared with other materials, the thermal conductivity of aluminum is 2000 times that of it, and the thermal conductivity of plastic is 30 times that of it. Therefore, wood has good thermal insulation properties.

6. Electrical insulation: The point conductivity of wood is poor, and it is a good electrical insulation material.

7. Machinability: Wood has a moderate degree of hardness and is easy to process. Mortise and tenon joints, nail joints and cementation are mostly seen among wood products, and various metal connectors; It can also be bent and compressed after cooking.

8. The disadvantages of wood are flammability, decay, insect-eaten, dry shrinkage and wet swelling.

9. Decorative: The wood itself has a naturally formed pattern, and as a furniture and decorative material, it has good decoration.

The ignition point of wood is:

The ignition point of wood is 200 -290, because wood is a mixture of materials, because the various components are different, the content of the components is different, so the ignition point is not fixed. And also with the dryness and humidity of the wood, texture, air humidity.

and other factors.

Combustible substances, whether solid, liquid or gaseous, if they coexist with air, will burn when they reach a certain temperature, and will continue to burn after the ignition source is removed. At this time, the lowest temperature of the combustible substance is called the ignition point, also known as the ignition point.

Generally, the ignition point of liquids is higher than the flash point, and flammable liquids.

The ignition point is 1 5 higher than the flash point.

1.Wood has good workability: wood has moderate hardness and is easy to cut and shape.

2.Good thermal insulation: The thermal insulation performance of wood is higher than that of steel and concrete, which can effectively insulate and keep warm.

3.Elasticity and toughness: Wood has good elasticity and toughness, which can disperse the force of the load.

4.Easy to repair: Wood furniture, doors and windows have the advantage of being easy to repair and restore to their original state if they are damaged.

5.Aesthetics: The natural grain of the wood gives people a beautiful and comfortable feeling.

6.Renewable: Wood is a naturally renewable resource that is sustainable relative to other building materials.

7.Strong moisture absorption and dehumidification: Wood has good humidity regulation ability, which can absorb and release water in the air.

8.Flame retardant function: Some wood has a certain flame retardant function after fireproof treatment.

9.There are many types of wood: different types of wood have different functional characteristics and can meet different needs.

10.Good sound absorption: wood has a good sound absorption effect, which can reduce noise.

But at the same time, wood also has the disadvantages of flammability, corrosion, and insect damage, so it needs to be protected when using.

Wood has very good mechanical properties, but wood is an organic heterogeneous material.

1. Green environmental protection, renewable and degradable;

2. The construction is simple and the construction period is short;

3. Warm in winter and cool in summer;

4. Excellent seismic performance.

Timber is a product of forest owners and plays a great supporting role in human life. Depending on the properties of wood, they are used in different ways, such as fuels and construction materials. Wood is a natural organic composite material consisting of a matrix of cellulose fibers (very tensile resistance) and lignin (high compression resistance).

General wood is defined as the xylem in which the stem grows secondarily.

There is about one trillion tons of wood on the planet, and about 10 million tons are added every year. Wood is a carbon-neutral renewable material with a large amount of reserves, and is one of the renewable energy sources that has attracted much attention. In 1991, about 3.5 million cubic metres of timber were produced, mainly for furniture and building structures.

The wood used as fuel is called firewood, and in rural areas, firewood is a commonly used fuel. Hardwoods are better used as fuel than softwoods because they burn longer and produce less smoke. In the winter months in Europe and North America, suburbanites use wood fires in their fireplaces to keep warm.

After the wood is distilled, charcoal is formed, the main component of which is carbon. In countries where fossil fuels are still not widely available, charcoal is also often used as the main fuel.

Wood has been an important building material since humans began to build houses. Before the nineteenth century, almost all ships were made of wood, and many are still wooden today. Elm trees, for example, are not easily damaged in wet conditions, and are particularly suitable for use on ships (before the invention of modern water pipes, elm trees were also used to make water pipes).

In the Middle Ages in Europe, oak was used for all wooden buildings, including beams, walls, doors and floors, and modern timber is more diverse, with poplar, pine and Douglas fir trees used for wooden doors.

Hardwood, softwood and timber strength.

Wood is generally classified into softwood and hardwood. Wood made from pine and cypress plants (like pine) is called cork, and wood made from dicots (like oak) is called hardwood.

However, the classification of softwoods and hardwoods is often misleading, because softwoods are not necessarily softer and hardwoods are not necessarily harder. Balsa woods, for example, are hardwoods, but softer than any softwood sold, and some softwoods (berry yew) are harder than many hardwoods.

There is a strong correlation between the type of tree and the nature of the wood being made. The density of wood varies with the species, and the strength of the wood is related to its density. For example, mahogany is a medium-density hardwood and is an excellent material for making furniture, while balsa wood has a low density and is often used to make model buildings or model airplanes.

1. The characteristics of wood in the third grade science book are combustible, processable, and do not produce harmful substances to the human body.

2. Wood can be burned, and this silver is the exothermic reaction between wood and oxidant, accompanied by flames, luminescence and smoke.

3. The wood can be processed, the softness and hardness of the wood are moderate, and it is easy to process without caution.

4. Wood does not produce substances harmful to the human body, that is, it is harmless to the human body.

5. Wood, one of the Chinese words, means a general term for trees that have been cut down. Wood is a product of forest owners and plays a great supporting role in human life, and people use it in different ways according to the different properties and characteristics of wood.

Metal is a substance with lustrous (i.e., strong reflection of visible light), malleable, easy to conduct electricity, heat and other properties. In nature, the vast majority of metals exist in a chemical state, and a few metals such as gold, platinum, silver, and bismuth exist in a free state. Most of the metal minerals are oxides and sulfides.

Other forms of existence are chlorides, sulfates, carbonates, and silicates.

Wood refers to firewood and wood, which is generally smaller in density than metal, does not conduct electricity, and most of them have good mechanical properties.

1. The characteristics of wood in the first volume of the third grade subject are combustible and processable, and it does not produce harmful substances to the human body.

2. Wood can be burned, that is, the exothermic reaction of wood and oxidant occurs in Hewan Hall, accompanied by flames, luminescence and smoke.

3. The wood can be processed, and the wood has a moderate degree of softness and hardness, and it is easy to process.

4. Wood does not produce substances harmful to the human body, that is, it is harmless to the human body.

5. Wood, one of the Chinese words, means a general term for trees that have been cut down. Wood is the product of forest owners, and Zen Yin plays a great supporting role in human life, and people use them in different ways according to the different properties and characteristics of wood.