2 thoughts on “Is the more pure the gold, the softened?”
Percy
Gold pure impure depends on how its density is in physics, and the mass of the volume of a material unit is called the density of this substance. 1. The quality of the mass of a certain substance to its volume, that is, the mass of a certain substance of the unit volume, is called this material density. Symbol. The international main unit is a kg/m^3, and the commonly used unit is also the gram/cm^3. The mathematical expression is ρ = m/v. In the international unit system, the main unit of quality is a kilogram, and the main unit of the volume is cubic meters, so the quality of 1 cubic meter material is used as the density of the material. Non -uniform substances are called "average density". 2. The physical meaning of density. With water, the density of water is 10^3 kg/m^3 or 1 gram/cm/cm^3 (1.0 × 10^3kg/m^3, physical) significance is: 1.0 × 10^3 kg. The average density of the earth is 5.5 × 10^3 kg/m^3. The average density of dry air under standard conditions is 0.001293 × 10^3 kg/m^3. M common non -metal solid, metal, liquid, and gas density (slightly). 3. refers to the mass of the material contained in the unit volume at the prescribed temperature. )express. It is mainly used in the measurement of quantity and delivery acceptance and quality control of certain oils, as well as simply judging oil performance. 4. In printing terms, the reflection density refers to a surface shading ability; transmitting density refers to the shielding ability of a filter. 5. The density of the sensitive material refers to the degree of image depth after its exposure is exposed. Such as film, the more transparent the picture is, the smaller the density; otherwise, the more opaque, the greater the density. The density is the physical quantity that reflects the material characteristics. The characteristics of the material refer to the nature of the material itself and can distinguish between each other. People often feel that the substances with high density are "heavy", and the substances with small density are "light". The "heavy" and "light" here are essentially the size of the density. : Quality is the amount of material contained in objects. The material is reduced, so the quality is reduced. Density is a characteristic of material. It does not change with changes in quality and volume, and the density of the same substance is unchanged. The density is a characteristic of matter. It is only related to the type of material, and it has nothing to do with factors such as quality and volume. Different substances and density are generally different, and the density of the same substance is the same. The formula of density: (ρ Represents density, M represents quality, V represents volume) When correctly understanding the density formula, pay attention to the special meanings of the conditions and each physical quantity. From the perspective of mathematics, there are three cases: (1) ρ must be proportional, m and v are proportional; (2) M. At a certain time, m is proportional to M. The physical significance, the three cases are only (1) correctly, (2) (3) are wrong. Because the density of the same substance is certain, it does not change with changes in volume and quality. Therefore, when understanding the physical formula, it is impossible to get out of physical affairs and cannot simply understand the relationship between the amount of physical formulas from the perspective of mathematics r r r r r r r r 5. The unit of density in the international unit system is: kg/ m 3. The correct reading method is kg per cubic meter, the symbol KG/m3, the commonly used unit is gram/cm 3, the correct reading method is grams per cubic centimeter, and the symbol is G/CM3. The conversion relationship between them: L g/cm3 = 1000kg/m3 6. The density value of water is 1000kg/m3 . The physical significance of its volume is 1m3 water quality It is 1000kg. 7. Deformation formula according to the density formula: m = v 为 or, V = m/ρ can calculate the quality and volume of the object, especially the problem of directly measurement of some quality and volume, such as calculation, not calculation, not calculation, not calculation. The volume of the rules, the quality of the monument, the quality of the monument. Density is one of the characteristics of the material. Each material 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, compare the density of the density and density tables in the measuring density table, and you can identify what matter the object is. 8. Use density knowledge to solve simple problems. If you judge whether the object is hollow, use the "analysis method" to solve some more complicated problems. The determination whether the object is hollow or solid. Generally there are three methods: (1) The formula formula, and then compare with the density of the material. If = ρ, it is solid. (2) Treat the object as a solid object, from the formula, find out, and then compare it. If u003C, it is hollow, if =, the object is solid. (3) Treat the object as a solid object, use, and find the quality of the solid object with a volume, and then compare the M to the actual quality M object of the object. If M = m object, the object is solid. 9. The density of the human body is only 1.07 g/cm3, which is only more density than water, so it should not be too difficult to learn swimming! The density of gasoline is smaller than water, so you know why the oil stains seen on the road will float on the water. The density of seawater is greater than water, and the human body is easier to float in seawater. The density of water is greater than ice. Now you go to the refrigerator to get some ice cubes, throw it in half a cup of water, and see if the ice cubes float? Still sinking. The density of material will be changed by temperature. Generally speaking, the quality of the material is not affected by temperature, but the volume will be hot and contracted. So when the temperature rises, the volume expands, and the density becomes smaller. On the contrary, the volume of the material is reduced when the temperature decreases, and the density will become larger. However, water is the exception, because the density of water is the largest at 4 ° C, and the density will become smaller as long as the water temperature rises or decreases from 4 ° C. In other words, water at 4 ° C is also swollen and cooling when heated. Therefore, the water always starts from the surface, and the water with the largest density of 4 ° C will sink into the bottom layer. This nature is very important. In the cold winter, although the surface of the water has frozen, the bottom layer of the lake still maintains about 4 ° C, so that the creatures in the water can spend the winter safely. The application of this paragraph [Application of Density] The application of density in production technology can be reflected from the following aspects. 1. Materials that can be identified. 2. The components of various substances contained in the object can be calculated. 3. The quality of some difficult objects can be calculated. 4. The volume of objects with complicated shapes can be calculated. 5. It can determine whether the object is solid or hollow. 6. Calculate the internal pressure of the liquid and buoyancy. The on, it can be seen that density has been widely used in scientific research and production and life. Dental density is an important basis for identifying unknown substances. "氩" is discovered by calculating the density of the unknown gas. After many experiments, it was analyzed by spectrum, and confirmed that the air contained a new gas that had not been known before, and named it 氩. It can be used to judge the fertility of the soil in agriculture. The soil fertilizer containing more humus is generally 2.3 × 103 kg/m 3. The fertility of the soil can be judged according to the density. When choosing seedlings, the seeds can be selected according to the sinking and floating situation of the seeds: full and strong seeds sink due to the large density; the shell and other weed seeds float on the water due to small density. In industrial production, the production of starch is based on potatoes. Generally speaking, the density of potatoes with more starch is large, so it can estimate the output of starch by determining the density of potatoes. For another example, before the factory cast metal objects, it is necessary to estimate how much metal melting is melted, which can calculate the required metal amount according to the volume of the mold and the density of the metal. The edit [Method of Metropolitania Testing] The method of measuring object density is diverse. You can develop students' thinking. , Testing the density Basic principles: ρ = m/v: 1. Illegal method: Equipment: balance, measuring cylinder, water, metal block, fine rope n Step: Step: 1. The quality of the metal block is called by Tianping; . Inject appropriate amount of water into the measuring cylinder, read the volume of V1, . Use a thin rope to stay in the metal block and put it in the measuring cylinder in a measuring cylinder with a thin rope and put it in the measuring cylinder in a measuring cylinder. In the middle, immersion, read the volume of V2. Calculating expression: ρ = m/(v2-v1) 2. The gravity cup method: n 1. Filled the water to the burn, and the quality is called M1 on the balance; . Put the metal block in the water gently, overflows part of the water, and then put the cup on the balance and the quality is called the quality of the quality. m2; . Take out the metal block and put the cup on the balance and call the cup and the quality of the remaining water M3. Calculating expression: ρ = ρ ρ (m2-m3)/(m1-m3) 3. The law of Archimedes: Step in the rope : 1. Tibet the metal block with a thin rope, and use the spring scale to call the gravity G of the metal block; 2. The metal block is completely immersed in the water, and the spring scale is called the metal block. Vision G/; Calculating expression: ρ = gρ water/(g-g/) 4. buoyancy method (1): , Measurement Step: 1. Inject an appropriate amount of water into the measuring cylinder, read the volume of V1; . Put the wooden block in the water, float, read the volume V2 after static; . Insert the wooden block with a fine needle, completely immerse the wooden block into the water, and read the volume of V3. A calculation expression: ρ = ρ ρ (V2-V1)/(V3-V1) 5, buoyancy method (2): Small plastic cup, small stone Step: 1. Put an appropriate amount of water in the cylindrical cup, then gently put the plastic cup in the mouth of the cup to let it float, use the scale ruler to test it The height of the water in the cup H1; 2. Put the small stones into the cup, float, and measure the height of the water with the scale ruler; . Take it out, put it in the water, sink, and use the scale to measure the height of the water H3. Calculate the expression: ρ = ρ ρ (H2-H1)/(H3-H1) 6, density meter, density meter Method: The equipment: egg, density meter, water, salt, glass cup Step: 1. Pour an appropriate amount of water in the glass, gently put the eggs in, sink the eggs, sink the eggs, ; . Swipes gradually add salt to the water, stir with a density meter while adding a density meter until the eggs float, and the density of the salt water is measured by the density meter. Liquid density 1. Illegal method: Equipment: cup, measuring cylinder, balance, liquid to be tested Step: The total quality of the liquid m1; 2. Pour the liquid (appropriate amount) in the cup into the measuring cylinder and measure the total quality of the remaining liquid and the cup with the sky flat; Volume V. A calculation expression: ρ = (m1-m2)/v 2. The gravity cup method Equipment: burn cup, water, liquid, balance n Step: 1 1 , Use the quality of the burning M1 with Tianping; 2. Pour water in the cup, call the total quality M2; . The water in the cup is wiped, dry, fill the cup and fill it up in the cup. To be tested, it is called the total quality M3. A calculation expression: ρ = ρ ρ (m3-m1)/(m2-m1) 3. The law of Archimedes: Stone and fine rope Step: 1. Tie small stones with fine rope, use spring scale to call the gravity G of small stones; . immerse the small stone into the water into the water into the water , Use spring scale to call the small stone vision G/; 3. Immersed the small stones into the liquid to be tested, and use the spring scale to call the small stone's vision G //. A calculation expression: ρ = ρ ρ (g-g //)/(g-g/) (Note: The condition of this method is: the liquid to be measured is insoluble in water, the density of the liquid to be measured is less than the water than the water than the water than the water. Dental) 4. Dental meter method: The density meter, density meter, liquid to be measured Methods: Put the density meter into the liquid to be tested and read the density directly. Edit this section [meaning of the physical particles, density ρ] The quantum mechanics clearly states that the meaning of the density of the density is that the particle is in the small area of the space in the space (mathematical term "the volume meta -in the volume meta -in the" volume meta ") The probability in it, the probability density.
In physics, the mass of the volume of a substance unit is called the density of this substance. 1. The quality of the mass of a certain substance and the volume, that is, the mass of a certain substance of the unit volume, is called this material density. Symbol. The international main unit is a kg/m^3, and the commonly used unit is also the gram/cm^3. The mathematical expression is ρ = m/v. In the international unit system, the main unit of quality is a kilogram, and the main unit of the volume is cubic meters, so the quality of 1 cubic meter material is used as the density of the material. Non -uniform substances are called "average density". 2, physical meaning of density. With water, the density of water is 10^3 kg/m^3 or 1 gram/cm/cm^3 (1.0 × 10^3kg/m^3, physical) significance is: 1.0 × 10^3 kg. The average density of the earth is 5.5 × 10^3 kg/m^3. The average density of dry air under standard conditions is 0.001293 × 10^3 kg/m^3. M common non -metal solid, metal, liquid, and gas density (slightly). 3. It refers to the mass of the material contained in the unit volume at the prescribed temperature. express. It is mainly used in the measurement of quantity and delivery acceptance and quality control of certain oils, as well as simply judging oil performance. 4. In printing terms, the reflection density refers to a surface shading ability; transmitting density refers to the lighting ability of a filter. 5. The density of the sensitive material refers to the degree of image depth after its exposure is exposed. Such as film, the more transparent the picture is, the smaller the density; otherwise, the more opaque, the greater the density. The density is the physical quantity that reflects the material characteristics. The characteristics of the material refer to the nature of the material itself and can distinguish between each other. People often feel that the substances with high density are "heavy", and the substances with small density are "light". The "heavy" and "light" here are essentially the size of the density. : Quality is the amount of material contained in objects. The material is reduced, so the quality is reduced. Density is a characteristic of material. It does not change with changes in quality and volume, and the density of the same substance is unchanged. The density is a characteristic of matter. It is only related to the type of material, and it has nothing to do with factors such as quality and volume. Different substances and density are generally different, and the density of the same substance is the same. The formula of density: (ρ Represents density, M represents quality, V represents volume) When correctly understanding the density formula, pay attention to the special meanings of the conditions and each physical quantity. From the perspective of mathematics, there are three cases: (1) ρ must be proportional, m and v are proportional; (2) M. At a certain time, m is proportional to M. The physical significance, the three cases are only (1) correctly, (2) (3) are wrong. Because the density of the same substance is certain, it does not change with changes in volume and quality. Therefore, when understanding the physical formula, it is impossible to get out of physical affairs and cannot simply understand the relationship between the amount of physical formulas from the perspective of mathematics r r r r r r r r 5. The unit of density in the international unit system is: kg/ m 3. The correct reading method is kg per cubic meter, the symbol KG/m3, the commonly used unit is gram/cm 3, the correct reading method is grams per cubic centimeter, and the symbol is G/CM3. r r r l g/cm3 = 1000kg/m3 6. The density value of water is 1000kg/m3 . The physical significance of its volume is 1m3 water quality It is 1000kg. 7. According to the deformation formula of the density formula: m = v 为 or, V = m/ρ can calculate the quality and volume of the object, especially some problems that are directly measured by quality and volume inconvenience, such as irregular calculations. The volume of the shape object, the quality of the monument, etc. Density is one of the characteristics of the material. Each material 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, compare the density of the density and density tables in the measuring density table, and you can identify what matter the object is. 8. Use density knowledge to solve simple problems. If you judge whether the object is hollow, use the "analysis method" to solve some more complicated problems. The determination whether the object is hollow or solid. Generally there are three methods: (1) The formula formula, and then compare with the density of the material. If = ρ, it is solid. (2) Treat the object as a solid object, from the formula, find out, and then compare it. If u003C, it is hollow, if =, the object is solid. (3) Treat the object as a solid object, use, and find the quality of the solid object with a volume, and then compare the M to the actual quality M object of the object. If M = m object, the object is solid. 9. The density of the human body is only 1.07 g/cm3, which is only more density than water, so it should not be too difficult to learn swimming! The density of gasoline is smaller than water, so you know why the oil stains seen on the road will float on the water. The density of seawater is greater than water, and the human body is easier to float in seawater. The density of water is greater than ice. Now you go to the refrigerator to get some ice cubes, throw it in half a cup of water, and see if the ice cubes float? Still sinking. The density of material will be changed by temperature. Generally speaking, the quality of the material is not affected by temperature, but the volume will be hot and contracted. So when the temperature rises, the volume expands, and the density becomes smaller. On the contrary, the volume of the material is reduced when the temperature decreases, and the density will become larger. However, water is the exception, because the density of water is the largest at 4 ° C, and the density will become smaller as long as the water temperature rises or decreases from 4 ° C. In other words, water at 4 ° C is also swollen and cooling when heated. Therefore, the water always starts from the surface, and the water with the largest density of 4 ° C will sink into the bottom layer. This nature is very important. In the cold winter, although the surface of the water has frozen, the bottom layer of the lake still maintains about 4 ° C, so that the creatures in the water can spend the winter safely. The application of this paragraph [Application of Density] The application of density in production technology can be reflected from the following aspects. 1. The materials that compose objects can be identified. 2. Calculate the ingredients of various substances in the object. 3. Calculate the quality of some difficult objects. 4. Calculate the volume of objects with complicated shapes. 5. You can determine whether the object is solid or hollow. 6. Calculate the internal pressure of the liquid and buoyancy. The on, it can be seen that density has been widely used in scientific research and production and life. Dental density is an important basis for identifying unknown substances. "氩" is discovered by calculating the density of the unknown gas. After many experiments, it was analyzed by spectrum, and confirmed that the air contained a new gas that had not been known before, and named it 氩. It can be used to judge the fertility of the soil in agriculture. The soil fertilizer containing more humus is generally 2.3 × 103 kg/m 3. The fertility of the soil can be judged according to the density. When choosing seedlings, the seeds can be selected according to the sinking and floating situation of the seeds: full and strong seeds sink due to the large density; the shell and other weed seeds float on the water due to small density. In industrial production, the production of starch is based on potatoes. Generally speaking, the density of potatoes with more starch is large, so it can estimate the output of starch by determining the density of potatoes. For another example, before the factory cast metal objects, it is necessary to estimate how much metal melting is melted, which can calculate the required metal amount according to the volume of the mold and the density of the metal. The edit [Method of Metropolitania Testing] The method of measuring object density is diverse. You can develop students' thinking. , Testing solid density Basic principles: ρ = m/v: 1, weighing method: R n1. The quality of the metal block is called by Tianping; 2, inject an appropriate amount of water into the measuring cylinder, read the volume of V1, 3, use a thin rope to stay in the metal block and put it in the measuring cylinder. Read the volume of V2. Calculating expression: ρ = m/(v2-v1) 2, the gravity cup method: N1, filled the water to the water, put the mass on the balance of M1; 2, gently put the metal block in the water, overflows part of the water, and then put the cup on the balance to the quality M2; 3, take out the metal block, put the cup on the balance, call the cup and the quality of the remaining water M3. Calculating expression: ρ = ρ ρ (m2-m3)/(M1-M3) 3, Akimide Law:
Step: 1. Use a thin rope to stay in the metal block and use a spring scale to call the gravity G of the metal block; 2, completely immerse the metal block into the water, use the spring scale to see the metal block in the water in the water View weight G/; Calculating expression: ρ = gρ water/(g-g/) 4, buoyancy method (1): n Step: 1. Inject an appropriate amount of water into the measuring cylinder, read the volume of V1; 2, put the wooden block in the water, float, read the volume V2 after static; Insert the wooden block, completely immerse the wooden block into the water, and read the volume of V3. A calculation expression: ρ = ρ ρ (V2-V1)/(V3-V1) 5, buoyancy method (2): Plastic cups, small stones Step: 1. Put an appropriate amount of water in the cylindrical cup, then gently put the plastic cup mouth on the mouth of the cup, let it float, measure the cup with scale ruler, measure the cup with a scale ruler, and measure the cup with a scale ruler. The height of Zhongshui H1; 2, gently put the small stone into the cup, float, measure the height of the water with the scale ruler; In the water, sink, and measure the height of the water with a scale ruler H3. Calculate the expression: ρ = ρ ρ (H2-H1)/(H3-H1) 6, density meter method: Equipment: Egg, density meter, water, salt, glass Step: 1, pour an appropriate amount of water in the glass, gently put the eggs in, sink the eggs; Gradually add salt to the water, stir with a density meter while adding the side until the eggs float, the density of the salt water is measured by density meter, and the density of the salt water is waited to the density of the egg; Illegal method: Equipment: cup, measuring cylinder, balance, liquid to be tested : 1, use the well -adjusted balance to the total quality of the burning cup and the liquid to be tested; 2. Pour the liquid (appropriate amount) in the cup into the measuring cylinder, and use the sky to measure the total mass of the remaining liquid and the cup of the cup; 3, read out the volume V of the liquid in the measuring cylinder. A calculation expression: ρ = (m1-m2)/v 2, the gravity cup method equipment: burn cup, water, wait for liquid, balance n Step: 1, use it with Tianping is called the quality of the burning M1; 2, pour water in the cup, calls the total quality M2; 3, pour the water in the cup, dry it, and pour the liquid to the cup. Called total quality M3. A calculation expression: ρ = ρ ρ (m3-m1)/(m2-m1) 3, Akimide Law: Equipment: spring scale, water, liquid to be tested, small stone, small stone, small stone, small stone, Block, thin rope Step: 1, use fine rope to stay with small stones, use spring scale to call the gravity G of small stones; 2, immerse the small stone into the water, use a spring scale scale scale Called the visual weight G/; 3, immerse the small stones into the liquid to be tested, and use the spring scale to call the small stone's visual weight G //. A calculation expression: ρ = ρ ρ (g-g //)/(g-g/) (Note: The condition of this method is: the liquid to be measured is insoluble in water, the density of the liquid to be measured is less than the water than the water than the water than the water. Deng) 4, density meter method: Equipment: density meter, liquid to be measured Methods: Put the density meter into the liquid to be tested and read the density directly. Edit this section [meaning of the physical particles, density ρ] The quantum mechanics clearly states that the meaning of the density of the density is that the particle is in the small area of the space in the space (mathematical term "the volume meta -in the volume meta -in the" volume meta ") The probability in it, the probability density.
Gold pure impure depends on how its density is in physics, and the mass of the volume of a material unit is called the density of this substance.
1. The quality of the mass of a certain substance to its volume, that is, the mass of a certain substance of the unit volume, is called this material density. Symbol. The international main unit is a kg/m^3, and the commonly used unit is also the gram/cm^3.
The mathematical expression is ρ = m/v. In the international unit system, the main unit of quality is a kilogram, and the main unit of the volume is cubic meters, so the quality of 1 cubic meter material is used as the density of the material. Non -uniform substances are called "average density".
2. The physical meaning of density. With water, the density of water is 10^3 kg/m^3 or 1 gram/cm/cm^3 (1.0 × 10^3kg/m^3, physical) significance is: 1.0 × 10^3 kg.
The average density of the earth is 5.5 × 10^3 kg/m^3.
The average density of dry air under standard conditions is 0.001293 × 10^3 kg/m^3.
M common non -metal solid, metal, liquid, and gas density (slightly).
3. refers to the mass of the material contained in the unit volume at the prescribed temperature. )express. It is mainly used in the measurement of quantity and delivery acceptance and quality control of certain oils, as well as simply judging oil performance.
4. In printing terms, the reflection density refers to a surface shading ability; transmitting density refers to the shielding ability of a filter.
5. The density of the sensitive material refers to the degree of image depth after its exposure is exposed. Such as film, the more transparent the picture is, the smaller the density; otherwise, the more opaque, the greater the density.
The density is the physical quantity that reflects the material characteristics. The characteristics of the material refer to the nature of the material itself and can distinguish between each other. People often feel that the substances with high density are "heavy", and the substances with small density are "light". The "heavy" and "light" here are essentially the size of the density.
: Quality is the amount of material contained in objects. The material is reduced, so the quality is reduced. Density is a characteristic of material. It does not change with changes in quality and volume, and the density of the same substance is unchanged.
The density is a characteristic of matter. It is only related to the type of material, and it has nothing to do with factors such as quality and volume. Different substances and density are generally different, and the density of the same substance is the same.
The formula of density: (ρ Represents density, M represents quality, V represents volume)
When correctly understanding the density formula, pay attention to the special meanings of the conditions and each physical quantity. From the perspective of mathematics, there are three cases:
(1) ρ must be proportional, m and v are proportional;
(2) M. At a certain time, m is proportional to M.
The physical significance, the three cases are only (1) correctly, (2) (3) are wrong. Because the density of the same substance is certain, it does not change with changes in volume and quality. Therefore, when understanding the physical formula, it is impossible to get out of physical affairs and cannot simply understand the relationship between the amount of physical formulas from the perspective of mathematics r r r r r r r r
5. The unit of density in the international unit system is: kg/ m 3. The correct reading method is kg per cubic meter, the symbol KG/m3, the commonly used unit is gram/cm 3, the correct reading method is grams per cubic centimeter, and the symbol is G/CM3.
The conversion relationship between them:
L g/cm3 = 1000kg/m3
6. The density value of water is 1000kg/m3
. The physical significance of its volume is 1m3 water quality It is 1000kg.
7. Deformation formula according to the density formula: m = v 为 or, V = m/ρ can calculate the quality and volume of the object, especially the problem of directly measurement of some quality and volume, such as calculation, not calculation, not calculation, not calculation. The volume of the rules, the quality of the monument, the quality of the monument. Density is one of the characteristics of the material. Each material 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, compare the density of the density and density tables in the measuring density table, and you can identify what matter the object is.
8. Use density knowledge to solve simple problems. If you judge whether the object is hollow, use the "analysis method" to solve some more complicated problems.
The determination whether the object is hollow or solid. Generally there are three methods:
(1) The formula formula, and then compare with the density of the material. If = ρ, it is solid.
(2) Treat the object as a solid object, from the formula, find out, and then compare it. If u003C, it is hollow, if =, the object is solid.
(3) Treat the object as a solid object, use, and find the quality of the solid object with a volume, and then compare the M to the actual quality M object of the object. If M = m object, the object is solid.
9. The density of the human body is only 1.07 g/cm3, which is only more density than water, so it should not be too difficult to learn swimming! The density of gasoline is smaller than water, so you know why the oil stains seen on the road will float on the water. The density of seawater is greater than water, and the human body is easier to float in seawater.
The density of water is greater than ice. Now you go to the refrigerator to get some ice cubes, throw it in half a cup of water, and see if the ice cubes float? Still sinking. The density of material will be changed by temperature. Generally speaking, the quality of the material is not affected by temperature, but the volume will be hot and contracted. So when the temperature rises, the volume expands, and the density becomes smaller. On the contrary, the volume of the material is reduced when the temperature decreases, and the density will become larger. However, water is the exception, because the density of water is the largest at 4 ° C, and the density will become smaller as long as the water temperature rises or decreases from 4 ° C. In other words, water at 4 ° C is also swollen and cooling when heated. Therefore, the water always starts from the surface, and the water with the largest density of 4 ° C will sink into the bottom layer. This nature is very important. In the cold winter, although the surface of the water has frozen, the bottom layer of the lake still maintains about 4 ° C, so that the creatures in the water can spend the winter safely.
The application of this paragraph [Application of Density]
The application of density in production technology can be reflected from the following aspects.
1. Materials that can be identified.
2. The components of various substances contained in the object can be calculated.
3. The quality of some difficult objects can be calculated.
4. The volume of objects with complicated shapes can be calculated.
5. It can determine whether the object is solid or hollow.
6. Calculate the internal pressure of the liquid and buoyancy.
The on, it can be seen that density has been widely used in scientific research and production and life. Dental density is an important basis for identifying unknown substances. "氩" is discovered by calculating the density of the unknown gas. After many experiments, it was analyzed by spectrum, and confirmed that the air contained a new gas that had not been known before, and named it 氩. It can be used to judge the fertility of the soil in agriculture. The soil fertilizer containing more humus is generally 2.3 × 103 kg/m 3. The fertility of the soil can be judged according to the density. When choosing seedlings, the seeds can be selected according to the sinking and floating situation of the seeds: full and strong seeds sink due to the large density; the shell and other weed seeds float on the water due to small density. In industrial production, the production of starch is based on potatoes. Generally speaking, the density of potatoes with more starch is large, so it can estimate the output of starch by determining the density of potatoes. For another example, before the factory cast metal objects, it is necessary to estimate how much metal melting is melted, which can calculate the required metal amount according to the volume of the mold and the density of the metal.
The edit [Method of Metropolitania Testing]
The method of measuring object density is diverse. You can develop students' thinking. , Testing the density
Basic principles: ρ = m/v:
1. Illegal method:
Equipment: balance, measuring cylinder, water, metal block, fine rope n Step: Step:
1. The quality of the metal block is called by Tianping;
. Inject appropriate amount of water into the measuring cylinder, read the volume of V1,
. Use a thin rope to stay in the metal block and put it in the measuring cylinder in a measuring cylinder with a thin rope and put it in the measuring cylinder in a measuring cylinder. In the middle, immersion, read the volume of V2.
Calculating expression: ρ = m/(v2-v1)
2. The gravity cup method:
n 1. Filled the water to the burn, and the quality is called M1 on the balance;
. Put the metal block in the water gently, overflows part of the water, and then put the cup on the balance and the quality is called the quality of the quality. m2;
. Take out the metal block and put the cup on the balance and call the cup and the quality of the remaining water M3.
Calculating expression: ρ = ρ ρ (m2-m3)/(m1-m3)
3. The law of Archimedes:
Step in the rope
:
1. Tibet the metal block with a thin rope, and use the spring scale to call the gravity G of the metal block;
2. The metal block is completely immersed in the water, and the spring scale is called the metal block. Vision G/;
Calculating expression: ρ = gρ water/(g-g/)
4. buoyancy method (1):
, Measurement
Step:
1. Inject an appropriate amount of water into the measuring cylinder, read the volume of V1;
. Put the wooden block in the water, float, read the volume V2 after static;
. Insert the wooden block with a fine needle, completely immerse the wooden block into the water, and read the volume of V3.
A calculation expression: ρ = ρ ρ (V2-V1)/(V3-V1)
5, buoyancy method (2):
Small plastic cup, small stone
Step:
1. Put an appropriate amount of water in the cylindrical cup, then gently put the plastic cup in the mouth of the cup to let it float, use the scale ruler to test it The height of the water in the cup H1;
2. Put the small stones into the cup, float, and measure the height of the water with the scale ruler;
. Take it out, put it in the water, sink, and use the scale to measure the height of the water H3.
Calculate the expression: ρ = ρ ρ (H2-H1)/(H3-H1)
6, density meter, density meter Method:
The equipment: egg, density meter, water, salt, glass cup
Step:
1. Pour an appropriate amount of water in the glass, gently put the eggs in, sink the eggs, sink the eggs, ;
. Swipes gradually add salt to the water, stir with a density meter while adding a density meter until the eggs float, and the density of the salt water is measured by the density meter. Liquid density
1. Illegal method:
Equipment: cup, measuring cylinder, balance, liquid to be tested
Step:
The total quality of the liquid m1;
2. Pour the liquid (appropriate amount) in the cup into the measuring cylinder and measure the total quality of the remaining liquid and the cup with the sky flat; Volume V.
A calculation expression: ρ = (m1-m2)/v
2. The gravity cup method
Equipment: burn cup, water, liquid, balance n Step:
1 1 , Use the quality of the burning M1 with Tianping;
2. Pour water in the cup, call the total quality M2;
. The water in the cup is wiped, dry, fill the cup and fill it up in the cup. To be tested, it is called the total quality M3.
A calculation expression: ρ = ρ ρ (m3-m1)/(m2-m1)
3. The law of Archimedes:
Stone and fine rope
Step:
1. Tie small stones with fine rope, use spring scale to call the gravity G of small stones;
. immerse the small stone into the water into the water into the water , Use spring scale to call the small stone vision G/;
3. Immersed the small stones into the liquid to be tested, and use the spring scale to call the small stone's vision G //.
A calculation expression: ρ = ρ ρ (g-g //)/(g-g/)
(Note: The condition of this method is: the liquid to be measured is insoluble in water, the density of the liquid to be measured is less than the water than the water than the water than the water. Dental)
4. Dental meter method:
The density meter, density meter, liquid to be measured
Methods: Put the density meter into the liquid to be tested and read the density directly.
Edit this section [meaning of the physical particles, density ρ]
The quantum mechanics clearly states that the meaning of the density of the density is that the particle is in the small area of the space in the space (mathematical term "the volume meta -in the volume meta -in the" volume meta ") The probability in it, the probability density.
In physics, the mass of the volume of a substance unit is called the density of this substance.
1. The quality of the mass of a certain substance and the volume, that is, the mass of a certain substance of the unit volume, is called this material density. Symbol. The international main unit is a kg/m^3, and the commonly used unit is also the gram/cm^3.
The mathematical expression is ρ = m/v. In the international unit system, the main unit of quality is a kilogram, and the main unit of the volume is cubic meters, so the quality of 1 cubic meter material is used as the density of the material. Non -uniform substances are called "average density".
2, physical meaning of density. With water, the density of water is 10^3 kg/m^3 or 1 gram/cm/cm^3 (1.0 × 10^3kg/m^3, physical) significance is: 1.0 × 10^3 kg.
The average density of the earth is 5.5 × 10^3 kg/m^3.
The average density of dry air under standard conditions is 0.001293 × 10^3 kg/m^3.
M common non -metal solid, metal, liquid, and gas density (slightly).
3. It refers to the mass of the material contained in the unit volume at the prescribed temperature. express. It is mainly used in the measurement of quantity and delivery acceptance and quality control of certain oils, as well as simply judging oil performance.
4. In printing terms, the reflection density refers to a surface shading ability; transmitting density refers to the lighting ability of a filter.
5. The density of the sensitive material refers to the degree of image depth after its exposure is exposed. Such as film, the more transparent the picture is, the smaller the density; otherwise, the more opaque, the greater the density.
The density is the physical quantity that reflects the material characteristics. The characteristics of the material refer to the nature of the material itself and can distinguish between each other. People often feel that the substances with high density are "heavy", and the substances with small density are "light". The "heavy" and "light" here are essentially the size of the density.
: Quality is the amount of material contained in objects. The material is reduced, so the quality is reduced. Density is a characteristic of material. It does not change with changes in quality and volume, and the density of the same substance is unchanged.
The density is a characteristic of matter. It is only related to the type of material, and it has nothing to do with factors such as quality and volume. Different substances and density are generally different, and the density of the same substance is the same.
The formula of density: (ρ Represents density, M represents quality, V represents volume)
When correctly understanding the density formula, pay attention to the special meanings of the conditions and each physical quantity. From the perspective of mathematics, there are three cases:
(1) ρ must be proportional, m and v are proportional;
(2) M. At a certain time, m is proportional to M.
The physical significance, the three cases are only (1) correctly, (2) (3) are wrong. Because the density of the same substance is certain, it does not change with changes in volume and quality. Therefore, when understanding the physical formula, it is impossible to get out of physical affairs and cannot simply understand the relationship between the amount of physical formulas from the perspective of mathematics r r r r r r r r
5. The unit of density in the international unit system is: kg/ m 3. The correct reading method is kg per cubic meter, the symbol KG/m3, the commonly used unit is gram/cm 3, the correct reading method is grams per cubic centimeter, and the symbol is G/CM3. r r r
l g/cm3 = 1000kg/m3
6. The density value of water is 1000kg/m3
. The physical significance of its volume is 1m3 water quality It is 1000kg.
7. According to the deformation formula of the density formula: m = v 为 or, V = m/ρ can calculate the quality and volume of the object, especially some problems that are directly measured by quality and volume inconvenience, such as irregular calculations. The volume of the shape object, the quality of the monument, etc. Density is one of the characteristics of the material. Each material 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, compare the density of the density and density tables in the measuring density table, and you can identify what matter the object is.
8. Use density knowledge to solve simple problems. If you judge whether the object is hollow, use the "analysis method" to solve some more complicated problems.
The determination whether the object is hollow or solid. Generally there are three methods:
(1) The formula formula, and then compare with the density of the material. If = ρ, it is solid.
(2) Treat the object as a solid object, from the formula, find out, and then compare it. If u003C, it is hollow, if =, the object is solid.
(3) Treat the object as a solid object, use, and find the quality of the solid object with a volume, and then compare the M to the actual quality M object of the object. If M = m object, the object is solid.
9. The density of the human body is only 1.07 g/cm3, which is only more density than water, so it should not be too difficult to learn swimming! The density of gasoline is smaller than water, so you know why the oil stains seen on the road will float on the water. The density of seawater is greater than water, and the human body is easier to float in seawater.
The density of water is greater than ice. Now you go to the refrigerator to get some ice cubes, throw it in half a cup of water, and see if the ice cubes float? Still sinking. The density of material will be changed by temperature. Generally speaking, the quality of the material is not affected by temperature, but the volume will be hot and contracted. So when the temperature rises, the volume expands, and the density becomes smaller. On the contrary, the volume of the material is reduced when the temperature decreases, and the density will become larger. However, water is the exception, because the density of water is the largest at 4 ° C, and the density will become smaller as long as the water temperature rises or decreases from 4 ° C. In other words, water at 4 ° C is also swollen and cooling when heated. Therefore, the water always starts from the surface, and the water with the largest density of 4 ° C will sink into the bottom layer. This nature is very important. In the cold winter, although the surface of the water has frozen, the bottom layer of the lake still maintains about 4 ° C, so that the creatures in the water can spend the winter safely.
The application of this paragraph [Application of Density]
The application of density in production technology can be reflected from the following aspects.
1. The materials that compose objects can be identified.
2. Calculate the ingredients of various substances in the object.
3. Calculate the quality of some difficult objects.
4. Calculate the volume of objects with complicated shapes.
5. You can determine whether the object is solid or hollow.
6. Calculate the internal pressure of the liquid and buoyancy.
The on, it can be seen that density has been widely used in scientific research and production and life. Dental density is an important basis for identifying unknown substances. "氩" is discovered by calculating the density of the unknown gas. After many experiments, it was analyzed by spectrum, and confirmed that the air contained a new gas that had not been known before, and named it 氩. It can be used to judge the fertility of the soil in agriculture. The soil fertilizer containing more humus is generally 2.3 × 103 kg/m 3. The fertility of the soil can be judged according to the density. When choosing seedlings, the seeds can be selected according to the sinking and floating situation of the seeds: full and strong seeds sink due to the large density; the shell and other weed seeds float on the water due to small density. In industrial production, the production of starch is based on potatoes. Generally speaking, the density of potatoes with more starch is large, so it can estimate the output of starch by determining the density of potatoes. For another example, before the factory cast metal objects, it is necessary to estimate how much metal melting is melted, which can calculate the required metal amount according to the volume of the mold and the density of the metal.
The edit [Method of Metropolitania Testing]
The method of measuring object density is diverse. You can develop students' thinking. , Testing solid density
Basic principles: ρ = m/v:
1, weighing method:
R n1. The quality of the metal block is called by Tianping;
2, inject an appropriate amount of water into the measuring cylinder, read the volume of V1,
3, use a thin rope to stay in the metal block and put it in the measuring cylinder. Read the volume of V2.
Calculating expression: ρ = m/(v2-v1)
2, the gravity cup method:
N1, filled the water to the water, put the mass on the balance of M1;
2, gently put the metal block in the water, overflows part of the water, and then put the cup on the balance to the quality M2;
3, take out the metal block, put the cup on the balance, call the cup and the quality of the remaining water M3.
Calculating expression: ρ = ρ ρ (m2-m3)/(M1-M3)
3, Akimide Law:
Step:
1. Use a thin rope to stay in the metal block and use a spring scale to call the gravity G of the metal block;
2, completely immerse the metal block into the water, use the spring scale to see the metal block in the water in the water View weight G/;
Calculating expression: ρ = gρ water/(g-g/)
4, buoyancy method (1):
n Step:
1. Inject an appropriate amount of water into the measuring cylinder, read the volume of V1;
2, put the wooden block in the water, float, read the volume V2 after static; Insert the wooden block, completely immerse the wooden block into the water, and read the volume of V3.
A calculation expression: ρ = ρ ρ (V2-V1)/(V3-V1)
5, buoyancy method (2):
Plastic cups, small stones
Step:
1. Put an appropriate amount of water in the cylindrical cup, then gently put the plastic cup mouth on the mouth of the cup, let it float, measure the cup with scale ruler, measure the cup with a scale ruler, and measure the cup with a scale ruler. The height of Zhongshui H1;
2, gently put the small stone into the cup, float, measure the height of the water with the scale ruler; In the water, sink, and measure the height of the water with a scale ruler H3.
Calculate the expression: ρ = ρ ρ (H2-H1)/(H3-H1)
6, density meter method:
Equipment: Egg, density meter, water, salt, glass
Step:
1, pour an appropriate amount of water in the glass, gently put the eggs in, sink the eggs; Gradually add salt to the water, stir with a density meter while adding the side until the eggs float, the density of the salt water is measured by density meter, and the density of the salt water is waited to the density of the egg;
Illegal method:
Equipment: cup, measuring cylinder, balance, liquid to be tested
:
1, use the well -adjusted balance to the total quality of the burning cup and the liquid to be tested;
2. Pour the liquid (appropriate amount) in the cup into the measuring cylinder, and use the sky to measure the total mass of the remaining liquid and the cup of the cup;
3, read out the volume V of the liquid in the measuring cylinder.
A calculation expression: ρ = (m1-m2)/v
2, the gravity cup method
equipment: burn cup, water, wait for liquid, balance n Step:
1, use it with Tianping is called the quality of the burning M1;
2, pour water in the cup, calls the total quality M2;
3, pour the water in the cup, dry it, and pour the liquid to the cup. Called total quality M3.
A calculation expression: ρ = ρ ρ (m3-m1)/(m2-m1)
3, Akimide Law:
Equipment: spring scale, water, liquid to be tested, small stone, small stone, small stone, small stone, Block, thin rope
Step:
1, use fine rope to stay with small stones, use spring scale to call the gravity G of small stones;
2, immerse the small stone into the water, use a spring scale scale scale Called the visual weight G/;
3, immerse the small stones into the liquid to be tested, and use the spring scale to call the small stone's visual weight G //.
A calculation expression: ρ = ρ ρ (g-g //)/(g-g/)
(Note: The condition of this method is: the liquid to be measured is insoluble in water, the density of the liquid to be measured is less than the water than the water than the water than the water. Deng)
4, density meter method:
Equipment: density meter, liquid to be measured
Methods: Put the density meter into the liquid to be tested and read the density directly.
Edit this section [meaning of the physical particles, density ρ]
The quantum mechanics clearly states that the meaning of the density of the density is that the particle is in the small area of the space in the space (mathematical term "the volume meta -in the volume meta -in the" volume meta ") The probability in it, the probability density.
That's it. My aunt originally had a gold pendant. The pure gold was bitten by my niece.