"Quality" Quality and Density PPT Courseware 4

Description

"Quality" Quality and Density PPT Courseware 4

Want to discuss

What are our desks and chairs made of? Which contains more wood, a desk or a chair? What about hammers and nails?

1. Quality

Lecture tables, chairs, hammers, and nails are called objects in physics, and the wood and iron that make up these objects are called "matter."

From the above observations, we can conclude that podiums and desks contain different amounts of wood; hammers and nails also contain different amounts of iron.

1. Definition

The amount of matter an object contains is called its mass. Symbol m.

Unit of mass:

1. The unit of mass in the International System of Units: kilogram (kg)

2. Other units: milligram (mg), gram (g), ton (t)

3.Unit conversion:

1t =____kg 1g =____kg 1mg =____kg

(class exercise)

(1)80mg= _____ g = kg

(2)0.5t= kg = g

2. Tools commonly used in laboratories to measure quality:

Pallet balances and physical balances

2. How to use pallet balance:

Before measurement

1. Place the balance on a level work surface

2. Move the cursor to the "0" mark on the left end of the ruler

3. Adjust the balance nut on the crossbeam so that the pointer is aligned with the scale line in the center of the indexing plate (how to adjust?)

When measuring

1. Place the object on the left pan of the balance and use tweezers to add or subtract weights to the right pan. (How to add and subtract weights?)

2. Move the position of the cursor on the ruler so that the pointer is aligned with the center line of the indexing plate.

Reading

The mass of the object is equal to the sum of the total mass of the weights in the right pan and the number on the left end of the upstream scale.

Mass of object = weight + swimming code

Precautions when using the balance

1. The mass of the weighed object must exceed the measuring range of the balance.

2. The weights should be picked up with tweezers, not by hand.

3. Adding weights should be from large to small, and subtracting weights should be from small to small.

4. When reading the quality value indicated by the travel code, the scale on the left should prevail.

5. After the measurement is completed, the weight should be put into the box and the weight should be returned to zero.

6. Keep the balance dry and clean. Do not put wet objects and chemicals directly into the balance pan, and do not make the weights dirty to avoid rust.

Summary of this section

1. Mass (m): The amount of matter contained in an object is called mass.

2. The international unit of mass is: kilogram (kg). Other commonly used units are: tons (t), grams (g), milligrams (mg).

3． The mass of an object does not change with shape, state, or location.

4. Quality measurement tools: Balances are commonly used in laboratories to measure quality. Commonly used balances include pallet balances and physical balances.

5. Correct use of balance:

(1) Place the balance on the horizontal platform and place the scale on the zero mark at the left end of the ruler;

(2) Adjust the balance nut so that the pointer points to the center line of the index plate, and the balance is now balanced;

(3) Place the object in the left pan, use tweezers to add or subtract weights to the right pan and adjust the position of the free weight on the scale until the beam returns to balance;

(4) At this time, the mass of the object is equal to the total mass of the weights in the right plate plus the scale value corresponding to the free weight.

6. When using the balance, please note:

(1) The maximum weighing capacity cannot be exceeded;

(2) Use tweezers when adding or subtracting weights, and move gently;

(3) Do not place wet objects and chemicals directly on the pallet.

Practice questions

1. Which of the following statements about quality is correct ( )

A. Mass is the size of a substance

B. The mass is the amount of the object

C. Mass is the amount of material contained in an object

D. Mass is the size of an object

2. Which of the following statements is correct ( )

A. The mass of the lunar module decreases from the earth to the moon.

B. 1kg of iron has greater mass than 1kg of cotton.

C. After the glass is broken, its quality remains unchanged.

D. After a glass of water solidifies into ice, its volume and mass also increase.

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For more information about the "Mass and Density Quality" PPT courseware, please click the Quality and Density ppt quality ppt tag.

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Update Time: 2024-07-31

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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