Download "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок"

"videoThumbnail Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок

6 класс, 28 урок, Модуль числа

6 класс, 28 урок, Модуль числа

Channel: Видеокурсы DA VINCI

Математический анализ, 24 урок, Интегрирование тригонометрических выражений

Математический анализ, 24 урок, Интегрирование тригонометрических выражений

Channel: DA VINCI Video Courses

Встреча миров. Великие географические открытия | Всемирная история 7 класс #3 | Инфоурок

Встреча миров. Великие географические открытия | Всемирная история 7 класс #3 | Инфоурок

Channel: ИНФОУРОК

Сила | Физика 7 класс #17 | Инфоурок

Сила | Физика 7 класс #17 | Инфоурок

Channel: ИНФОУРОК

Мгновенная скорость. Сложение скоростей | Физика 10 класс #4 | Инфоурок

Мгновенная скорость. Сложение скоростей | Физика 10 класс #4 | Инфоурок

Channel: ИНФОУРОК

Реактивное движение. Ракеты | Физика 9 класс #21 | Инфоурок

Реактивное движение. Ракеты | Физика 9 класс #21 | Инфоурок

Channel: ИНФОУРОК

инфоурок

школа

видеоуроки

7 класс

физика

00:00:00

[music]

00:00:10

force of friction static friction

00:00:15

we already know that the reason for the change in

00:00:17

speed is the friction force a ball

00:00:20

coming down a hill

00:00:21

moves along a horizontal path

00:00:23

unevenly its speed gradually

00:00:26

decreases and after a while it

00:00:28

stops

00:00:30

the skater as soon as it stops

00:00:32

accelerating will roll for quite a

00:00:34

long time but will still stop

00:00:37

stops and the car, after the

00:00:40

engine stops working, when the

00:00:43

surfaces of two bodies come into contact, an

00:00:45

interaction arises between them,

00:00:47

which begins to impede their

00:00:49

movement relative to each other,

00:00:51

this interaction is called

00:00:54

friction, the force that characterizes this

00:00:58

interaction is called the friction force,

00:01:01

it is denoted by the letter f with the index

00:01:04

tr. Let's consider the reasons

00:01:07

that determine the occurrence of

00:01:10

friction force. 1 of the reasons is the roughness of

00:01:13

the surface of the contacting bodies, even

00:01:16

smooth-looking ones have irregularities.

00:01:18

So, with magnification, the

00:01:21

irregularities on the razor blade are clearly visible. Let's look

00:01:23

under a microscope at the razor blade

00:01:25

on which a human hair lies.

00:01:28

It is obvious that scratches and micro irregularities are

00:01:31

very small,

00:01:32

but with the movement of one body along the

00:01:34

surface of another, these irregularities,

00:01:36

tubercles and depressions clinging to each

00:01:38

other, create

00:01:40

a certain force that retards movement;

00:01:43

another reason for friction is the mutual

00:01:45

attraction of molecules of contacting bodies,

00:01:48

if the surfaces are well polished, then

00:01:51

when they come into contact,

00:01:52

some of the molecules can approach at a

00:01:55

distance sufficient for their

00:01:57

interaction, in this case it begins

00:02:00

the attraction between

00:02:02

the molecules of bodies

00:02:03

in contact with each other is noticeable; there are

00:02:06

different types of dry friction; the first is

00:02:09

static friction; the

00:02:11

second is sliding friction; the third is rolling friction;

00:02:28

response to the

00:02:32

actions of our force, a

00:02:34

frictional force sharply arises between the floor

00:02:37

and the legs of the sofa; the balancing

00:02:39

actions of our force when the body is at

00:02:42

rest on an inclined plane, it is

00:02:45

held on it by the force of friction;

00:02:47

however, if there were no friction, then the body,

00:02:50

under the influence of gravity, would begin to

00:02:53

slide down the inclined plane planes

00:02:54

like a sled down a mountain, since this force

00:02:58

exists between

00:03:00

bodies at rest relative to each other, this force is

00:03:02

usually called the

00:03:03

static friction force due to static friction

00:03:07

on a conveyor belt I

00:03:08

move parts in production,

00:03:11

for example, the picture shows a

00:03:13

conveyor moving waste from a

00:03:15

woodworking industry, the

00:03:17

static friction force holds a wedge driven

00:03:21

into the deck prevents the tape from coming undone;

00:03:23

tied in a knot, holds the

00:03:26

face cream on the skin, preventing it from slipping off, and

00:03:29

so on; the friction that occurs when

00:03:32

one body slides over the surface of

00:03:34

another

00:03:35

is called sliding friction; such friction

00:03:38

occurs, for example, when moving skates;

00:03:41

if instead of a skate blade there are wheels,

00:03:44

then such a movement called rolling

00:03:47

roller skates roll they slide along the

00:03:50

surface of the earth

00:03:51

the friction that arises is called

00:03:54

rolling friction the movement of the wheels of a

00:03:57

railway train rolling logs

00:03:59

coils with cable rolling a ball

00:04:02

along a chute all this is a manifestation of the

00:04:05

rolling friction force the friction force can be

00:04:09

reduced many times

00:04:10

if introduced between the rubbing

00:04:12

surfaces the lubricant will not come into contact with the

00:04:16

surfaces of the

00:04:17

donkey's body and lubricant friction of layers of liquid lubricant

00:04:21

less than solid surfaces, for example,

00:04:24

weak friction when skating on

00:04:26

ice and skiing on snow can be explained by the

00:04:29

action of the lubricant due to the strong pressure

00:04:32

between the skates and the ice, a

00:04:35

thin layer of water is formed between the skates and the snow.

00:04:37

in practical life,

00:04:40

various oils are widely used as lubricants since

00:04:43

they stay on the surface longer; the

00:04:45

figure shows a body

00:04:48

moving on an inclined plane; the

00:04:51

velocity vector is indicated next to the body; indicate

00:04:54

the direction of the friction force; in both cases,

00:04:59

friction will be directed along

00:05:01

the surface of contact of the bodies; the

00:05:03

side opposite to the movement of the body will be

00:05:07

considered. what does the magnitude of the friction force depend on?

00:05:10

Let’s conduct an experiment to a wooden block;

00:05:14

attach a dynamometer to measure the

00:05:18

sliding friction force of a wooden block on a

00:05:20

smooth table and sandpaper; hold

00:05:23

the dynamometer horizontally; then

00:05:26

move the block evenly, first on a

00:05:28

smooth table, then on sandpaper;

00:05:33

draw a conclusion when moving on

00:05:36

sandpaper; the friction force more than on a

00:05:38

smooth table, which means the friction force will be

00:05:42

different depending on the materials of the

00:05:44

rubbing surfaces experiment 2,

00:05:49

attach a dynamometer to a wooden block,

00:05:52

measure the friction force by

00:05:54

evenly moving the block on a smooth

00:05:56

table, holding the dynamometer horizontally,

00:05:59

then put a load on the block and

00:06:02

similarly measure the friction force, we will

00:06:05

conclude that the greater the weight body, the

00:06:08

friction force is greater with the same

00:06:11

contact surface, which means the friction force

00:06:14

depends on the force pressing the body to the

00:06:16

surface experiment 3, replace

00:06:21

sliding friction with rolling friction by placing a

00:06:24

wooden block on round sticks,

00:06:27

measure the friction force, we will conclude that when

00:06:31

moving on a rough surface,

00:06:34

rolling friction is much less than the

00:06:36

sliding friction force Let's

00:06:38

summarize by measuring the force with which

00:06:41

the dynamometer acts on a body during its

00:06:43

uniform motion, we are measuring force 3

00:06:46

not the friction force will depend on the materials of the

00:06:50

rubbing surfaces, the forces pressing

00:06:54

the body to the surface

00:06:56

under equal loads, the rolling friction force is

00:06:58

always less than the sliding friction force

Description:

Видеоуроки являются идеальными помощниками при изучении новых тем, закреплении материала, для обычных и факультативных занятий, для групповой и индивидуальной работы. Они содержат оптимальное количество графической и анимационной информации для сосредоточения внимания и удержания интереса ребят без отвлечения от сути занятия. Каждый видеоурок озвучен профессиональным мужским голосом, четким и приятным для восприятия. Ученики ценят оригинальность подачи материала, родители радуются повышению отметок детей, а учителя в восторге от эффекта и экономии времени и денег при подготовке к урокам. ____________________________________ ★Инфоурок★ Крупнейший в России образовательный онлайн-проект МЫ ПРЕДЛАГАЕМ: ✓ Курсы дополнительного образования детей и взрослых: https://infourok.ru/ ✓ Тесты для учителей и воспитателей: https://infourok.ru/tests ✓ Самые массовые международные дистанционные олимпиады: https://infourok.ru/konkurs ✓ Видеоуроки по 14 предметам: https://school.infourok.ru/videouroki?authChecked=true ✓ Каталог репетиторов: https://school.infourok.ru/?authChecked=true ✓ Библиотека методических материалов для учителей: https://infourok.ru/biblioteka Адрес редакции и издательства: 214011, РФ, г. Смоленск, ул. Верхне-Сенная, 4. [email protected] © 2012–2017 Издатель: Проект «Инфоурок»

Preparing download options

Popular

HD video

Only sound

All

* — If the video is playing in a new tab, go to it, then right-click on the video and select "Save video as..."

** — Link intended for online playback in specialized players

Questions about downloading video

How can I download "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок" video?

http://unidownloader.com/ website is the best way to download a video or a separate audio track if you want to do without installing programs and extensions.
The UDL Helper extension is a convenient button that is seamlessly integrated into YouTube, Instagram and OK.ru sites for fast content download.
UDL Client program (for Windows) is the most powerful solution that supports more than 900 websites, social networks and video hosting sites, as well as any video quality that is available in the source.
UDL Lite is a really convenient way to access a website from your mobile device. With its help, you can easily download videos directly to your smartphone.

Which format of "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок" video should I choose?

The best quality formats are FullHD (1080p), 2K (1440p), 4K (2160p) and 8K (4320p). The higher the resolution of your screen, the higher the video quality should be. However, there are other factors to consider: download speed, amount of free space, and device performance during playback.

Why does my computer freeze when loading a "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок" video?

The browser/computer should not freeze completely! If this happens, please report it with a link to the video. Sometimes videos cannot be downloaded directly in a suitable format, so we have added the ability to convert the file to the desired format. In some cases, this process may actively use computer resources.

How can I download "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок" video to my phone?

You can download a video to your smartphone using the website or the PWA application UDL Lite. It is also possible to send a download link via QR code using the UDL Helper extension.

How can I download an audio track (music) to MP3 "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок"?

The most convenient way is to use the UDL Client program, which supports converting video to MP3 format. In some cases, MP3 can also be downloaded through the UDL Helper extension.

How can I save a frame from a video "Сила трения. Трение покоя | Физика 7 класс #23 | Инфоурок"?

This feature is available in the UDL Helper extension. Make sure that "Show the video snapshot button" is checked in the settings. A camera icon should appear in the lower right corner of the player to the left of the "Settings" icon. When you click on it, the current frame from the video will be saved to your computer in JPEG format.

What's the price of all this stuff?

It costs nothing. Our services are absolutely free for all users. There are no PRO subscriptions, no restrictions on the number or maximum length of downloaded videos.