"Scientific Inquiry: Density of Matter" Mass and Density PPT Courseware 3

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"Scientific Inquiry: Density of Matter" Mass and Density PPT Courseware 3

[Experience] The relationship between the mass and volume of an object

Activity 1: Take two iron blocks with different volumes and compare their masses.

Activity 2: Take two iron and wooden blocks of the same volume and compare their masses.

(1) In activity 1, the larger iron block has a greater mass than _______.

(2) In Activity 2, _______ (choose between "iron block" and "wooden block") has a larger mass.

Tips: (1) Big (2) Iron block

Doubtful about preview

1. What is the relationship between the mass and volume ratios of the same substance? What is the relationship between the mass and volume ratios of different substances?

2.What is the density of matter?

3. How to describe the formula of density?

4. What are the units of density? What is the relationship between them?

Explore 1 The relationship between mass and volume of matter

1. Conjecture and hypothesis: Combining "experience" and daily life experience, you think that the mass of the same substance with the same volume is _______, and the mass of different substances with the same volume is _______.

Tip: Based on experience in daily life, we know that the same material has the same mass when its volume is the same; the mass of different types of materials is generally different when the volume is the same.

Reference answer: Same or different

2. Experimental method: ____________________.

Tip: To explore the relationship between mass and volume of the same substance, you need to control the type of substance to be the same, change the volume, and study the relationship between mass and volume. This method is called the controlled variable method.

Reference answer: Control variable method

3. Experimental equipment: The measured physical quantity is ______, and the required equipment is ______.

Tip: In order to explore the relationship between the mass and volume of an object, you need to use a balance to measure the mass of the object and a graduated cylinder to measure the volume of the object.

Reference answer: mass and volume of objects, balance, measuring cylinder (any other reasonable equipment is acceptable)

Exploration 2 Density

Combined with Exploration 1, think about the following questions:

1. Through the above exploration experiment, we can know that the ratio of the mass to volume of the same substance is constant, but the ratio of the mass to volume of different substances is different. In physics, the ratio of density, that is, ____________ is used to reflect this characteristic of matter.

Reference answer: The mass of a certain substance and the volume of the substance

2. How to calculate density based on the definition of density? How to get the unit of density from the formula of density?

Reference answer: Density ρ is numerically equal to the ratio of mass m to volume V, so it is expressed as ρ = m/v; in the International System of Units, the unit of mass is kg and the unit of volume is m3, so the international unit of density is The unit is kg/m3, and other commonly used units are g/cm3.

3. Why is density a characteristic of matter?

Reference answer: (1) Each substance has its determined density. For the same substance, its density is unchanged under the same conditions, and its mass is proportional to its volume. (2) Different substances generally have different densities. (3) Density of matter and physical substance

Quantity, volume, shape, state of motion, etc. are irrelevant. It cannot be said that ρ is directly proportional to m or ρ is inversely proportional to V.

Knowledge summary

1. The relationship between mass and volume of matter

1.The ratio of mass to volume of the same substance is _____.

2. The ratio of mass to volume of different substances is _____.

2. Density

1. Definition: The mass of a substance divided by the volume of the substance.

2.Formula:_______.

3. Unit: Conversion: 1g/cm3=______kg/m3.

[Extended] Methods of analyzing and processing data

When exploring the rules between physical quantities, multiple sets of corresponding data about these physical quantities must be measured and recorded in tables for analysis and comparison. When analyzing and processing data, we need to "find differences in similarities and similarities in differences". Commonly used methods include: (1) Analyze the trend of one physical quantity changing with the size of another physical quantity, and obtain the qualitative relationship between physical quantities; (2) Calculate the values ​​in the table The data is used to obtain the quantitative relationship between physical quantities; (3) Draw points in the coordinate system to make an image, and combine mathematical knowledge to analyze the relationship between physical quantities.

Test Point 1 The relationship between mass and volume of matter

[Typical Example 1] In order to study a certain property of matter, a student used two different liquids A and B to conduct experiments. During the experiment, he used a graduated cylinder and a balance to measure the mass of liquid A (or B) at the same volume. The table records the experimental data and the obtained ratio of mass to volume.

(1) Analyzing the multiple relationship between the volume and mass changes of experiment numbers 1, 2, 3 or 4, 5, 6 in the table, the conclusion that can be drawn is _______________.

(2) Analyzing the experiment number ______ in the table, the conclusion can be drawn that two liquids A and B with the same volume have different masses.

(3) Analyzing the relationship between the mass and volume ratios of the two liquids A and B in the table can be summarized as __________________.

[Concise Lecture and Analysis] This question examines the relationship between mass and volume of matter. By analyzing the data of experiment numbers 1, 2, 3 or 4, 5, and 6, it can be found that for the same substance, the volume increases several times and the mass also increases several times. When two liquids A and B have the same volume, the experimental numbers are 1 and 4 (just reasonable), but their masses are different. Observing the ratio of mass to volume of two liquids A and B, you will find that the ratios are the same for the same substance, but different for different substances.

Answer: (1) The mass and volume of the same substance are directly proportional (or the mass increases several times as the volume increases) (2) 1 and 4 (reasonable) (3) The mass and volume of the same substance The ratio of the mass to the volume of different substances is generally different.

1. People usually say "gold is heavier than iron", which actually means ()

A.The volume of gold is larger than the volume of iron

B. The mass of gold is greater than the mass of iron

C. The price of gold is higher than the price of iron

D.The density of gold is greater than that of iron

[Analysis] Choose D. This question tests your understanding of the concept of density. "Gold is heavier than iron" means that when the volume is the same, the mass of gold is greater than the mass of iron, that is, the density of gold is greater than the density of iron.

2. There are often scenes like this in some feature films: a high wall collapses on everyone (actors), causing injuries. But in actual filming, the collapsed high wall will not hurt the actors. The blocks building such a high wall are most likely (　)

A. Mud bricks B. Metal blocks

C. Foam plastic block D. Cement brick

[Analysis] Choose C. This question tests the application of density knowledge. From the title "Collapsing high walls will not harm actors", we can see that the mass and hardness of such high wall blocks are relatively small. Under the same shape (volume), the smaller the density, the smaller the mass, and the less stable it is. It is easy to hurt the actors; judging from the materials given in the question, they can only be foam blocks.

3. During the burning process of the candle, its ()

A. The mass remains unchanged, the volume becomes smaller, and the density becomes larger.

B. The mass becomes smaller, the volume becomes smaller, and the density remains unchanged.

C. The mass becomes smaller, the volume remains unchanged, and the density becomes smaller.

D. Mass, volume, and density all become smaller.

[Analysis] Choose B. This question tests your understanding of density. As the candle burns, its mass and volume decrease, but the substance of the candle does not change, so its density remains unchanged.

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Update Time: 2024-05-31

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