What is the density of different substances? What is density a type of substance?

The principal unit of density in the International System of Units is "kilogram meter 3", which is something that most students can master, but many students find it difficult to convert units. For example, the density of iron is 78 103 kg m3 g cm3.

This problem can be solved by using the basic method in unit conversion, that is, how many times the unit in the molecule becomes smaller, and the converted value becomes several times larger: 1 kilogram 103 grams; How many times the unit in the denominator becomes smaller, and how many times the converted value becomes: 1 m 3 106 cm 3, thus, 7 8 10 kg m 3 7 8 103 (103 106) g cm 3 7 8 g cm3; According to this conversion method; There is a law in the unit of density that can be concluded by analyzing, namely:

For the density of a substance, the values are the same when the units are used as "gram centimeters3", "kilogram decimeters3", and "tons of meters3", respectively. For example, the density of iron, according to this law, can be known: water 7 8 g cm 3 7 8 kg decim 3 7 8 tons m3.

This "7 8" is obtained by removing 103 from the density value of iron in the density table in the textbook. Keeping this rule in mind not only brings great convenience to the conversion of density units, but also makes some problems involving density calculations simpler. For example, if you use this method to calculate the mass of water, the mass of 1 cm3 (ml) of water is 1 gram, the mass of 1 decimeter3 (liter) of water is 1 kg, and the mass of 1 meter3 of water is 1 ton.

Neither milk nor cement is of fixed density.

Because milk has differences in origin and composition.

Cement is also formulated, and the composition is different.

So there is no fixed, single density.

Weigh the quality of the beaker first.

Then fill the cup with water, put it on the balance to weigh its mass, and subtract the beaker mass to find its volume using the density formula.

Then pour the water into the milk and weigh the milk in the same way.

It would be nice to find its density using the density formula.

Density is a property of matter.

Unit volume. The mass of a certain substance is called the density of the substance, which is related to the type and state of the substance, and has nothing to do with the mass, volume and other factors.

Density in agricultural, industrial, scientific applications

1. Agriculture.

It is an important criterion for density. In agriculture, it can be used to judge the fertility of the soil, which contains humus.

The soil is mostly fertile, and its density is generally kilogram meters.

When we select seeds, we can select seeds according to the sinking and floating conditions of the seeds in the water: the full and robust seeds sink due to high density; Deflated husks and other weed seeds float on the surface of the water due to their low density. In industrial production, for example, the production of starch uses potatoes as raw materials, and generally speaking, the density of potatoes with more starch is larger, so the yield of starch can be estimated by measuring the density of potatoes.

2. Industrial.

Before casting the metal, the factory needs to estimate how much metal will be melted, and the amount of metal required can be calculated based on the volume of the mold and the density of the metal.

3. Scientifically.

1) Identify the materials that make up the object.

Density is one of the properties of matter, each substance has a certain density, and the density of different substances is generally different. Therefore, we can use density to identify substances. The method is to determine the density of the substance to be measured, and the measured density and density table.

By comparing the densities of various substances, it is possible to identify what substances are made of objects.

2) Calculate the composition of various substances contained in the object.

3) Calculate the mass of an object that is difficult to weigh or the volume of an object with a complex shape.

According to the variant of the density formula: m=v or v=m, the mass and volume of the object can be calculated, especially for some problems where the mass and volume are inconvenient to measure directly, such as calculating the volume of an irregularly shaped object, the mass of a monument, etc.

The above content reference: Encyclopedia - Density.

In physics, the mass of a substance per unit volume is called the density of that substance.

1. The ratio of the mass of a substance to its volume, that is, the mass of a substance per unit volume, is called the density of such a substance. Symbol. The unit is kilogram meter 3.

Its mathematical expression is =m v. In the International System of Units, the principal unit of mass is the kilogram and the principal unit of volume is the cubic meter, so the mass of 1 cubic meter of matter is taken as the density of the substance. For inhomogeneous substances, this is called "average density".

2. The physical meaning of density. For example, the density of water at 4 is 10 3 kg m 3 or 1 g cm 3 (, physical) meaning is: the mass of water per cubic meter is kg.

The average density of the Earth is kilogram m3.

The average density of dry air under standard conditions is 3 kilograms.

Density of common non-metallic solids, metals, liquids, gases (omitted).

3.Refers to the mass of a substance contained in a unit volume at a specified temperature, expressed in kg m 3 (read as kilograms per cubic meter) or g cm 3 (read as grams per cubic centimeter). It is mainly used for the measurement of conversion quantity and delivery acceptance, the quality control of certain oil products, and the simple judgment of oil performance.

4.In printing terms, reflective density refers to the shading ability of a surface; Transmittance refers to the shading ability of a filter.

5.The density of the photosensitive material refers to the degree of depth of the image after it has been developed. For example, in film, the more transparent the picture, the smaller the density; Conversely, the more opaque the place, the denser it becomes.

Density is a physical quantity that reflects the characteristics of matter, the property of matter refers to a property that the substance itself has and can be distinguished from each other, people often feel that the material with high density is "heavy", and the material with low density is "lighter", where "heavy" and "light" essentially refer to the size of density.

Mass is the amount of matter contained in an object. The substance contained is reduced, so the mass is reduced. Density is a property of matter, it does not change with the change of mass and volume, and the density of the same substance does not change.

Density is a physical property of matter that does not vary with shape and spaceGeographical locationChange and change are the characteristics of a substance that can be identified to a certain extent by the type of substance.

Generally speaking, no matter what substance it is in, no matter what state it is in, with the change of temperature and pressure, the volume or density will also change accordingly.

Note. The density of the human body is only g cm, which is only a little more dense than water. Gasoline is less dense than water, so oil stains you see on the road will float on the water. Seawater is denser than water, so it is easier for the human body to float in seawater.

Dead Sea. The density of the sea reaches a density greater than that of the human body, so that people can float in the Dead Sea.

Categories: Education, Science, >> Science & Technology.

Problem description: such as aluminum, lead, etc.

Analysis: Common solids.

Substance Density (kg m3) Substance Density (kg m3) Styrofoam Zinc.

Cork cast iron.

Paraffin wax steel.

Copper matte. brick silver.

Concrete lead.

Glass gold. Aluminum, platinum.

Common liquids. Substance Density (kg m3) Substance Density (kg m3) Gasoline Pure water.

Ether seawater.

Alcohol milk.

Kerosene sulfuric acid.

Diesel mercury. Common gases. Substance Density (kg m3) Matter Density (kg m3) Hydrogen Air.

Helium and oxygen. Water vapor carbon dioxide.

Carbon monoxide chlorine.