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1. When the contact surface is vertical,
the friction force is equal to the pressure f times the friction coefficient μ
at this time, the pressure is not gravity
gravity has no effect on the contact surface

n = mg, i.e. F, on horizontal ground= μ Mg because the gravity acts vertically on the plane
when the contact surface and the horizontal plane are not equal to 90 & # 186; As shown in the figure,

n = mg × cos θ < br />f= μ× mg × cos θ

(
the above conditions hold when the contact surface is rough
if the contact surface is smooth
there is no friction force)

2. In general, when pushing horizontally, the static friction is equal to the thrust; For example, if the horizontal thrust of 100N is used to push the table without pushing, the static friction is 100N
when there is no other force in the vertical direction, the static friction is equal to the gravity; For example, hold the bottle in your hand and keep it still. The static friction is equal to the gravity
it is better to analyze the direction and size of static friction according to the balance of force.

3. Dynamic friction = gravity * dynamic friction coefficient
(as long as the same object is on the same plane, no matter what motion it makes, the dynamic friction will not change, When an object is pushed by you, if the thrust is equal to the friction force, then the object will move in a straight line at a constant speed
if the thrust is greater than the friction force, then the object will move in a straight line at a constant speed)

static friction = the force you push the object

the difference between dynamic friction and static friction is that if the minimum force you push the object is 50N, then the object will move in a straight line at a constant speed The static friction force on a body is equal to the force you push it. At this time, it will not move. When the force you push the body is greater than 50N, the body will be pushed by you. At this time, the dynamic friction force on the body is calculated by the proct of positive pressure and friction coefficient. At this time, the dynamic friction force on the body must be less than the force you push it, otherwise it will not move

4.

The friction is only related to the pressure. It has nothing to do with gravity

analysis:

when the object moves on the horizontal ground, the friction force is related to pressure and gravity. Because for an object standing on a horizontal surface, the pressure is equal to gravity

When the object moves on the inclined plane, the friction force is related to the pressure, but not to the gravity. Because on the slope, pressure is not equal to gravity

So: the friction force is related to the pressure

< H2 > extended data:

basic overview of friction:

friction is related to objects that are rubbing against each other. Therefore, the description of friction in physics is neither generalized nor as accurate as other forces. Without friction, shoelaces can't be fastened, and screws and nails can't hold objects

The biggest difference in friction is between static friction and other friction. Some people think that static friction should not actually be counted as friction. Other frictional forces are related to dissipation: it reces the relative velocity of objects that rub against each other and converts mechanical energy into heat energy

The friction between solid surfaces can be divided into sliding friction, rolling friction, static friction, rolling friction and rotational friction. In engineering, lubricants are used to rece friction. If two surfaces are separated by a layer of liquid, liquid friction can occur between them. If the separation of liquid is not complete, mixed friction may also occur. Air track works by air friction. The working principle of lubricant and air track is to use "liquid or gas (i.e. fluid) friction to replace solid friction" to work

If lubricant, liquid or gas flows along a solid surface, its velocity will be reced e to the influence of friction. The structure of the solid surface has little effect on the friction, and the most important one is the cross-sectional area of the fluid. The reason is that there is friction not only at the interface between the fluid and the solid, but also between different layers in the fluid, and the velocity of the fluid varies with the distance from the solid surface

an object moving relative to a fluid is resisted. This resistance is in the opposite direction of its motion. In the case of laminar flow, the resistance is proportional to its velocity. In turbulence, the resistance is proportional to the square of its velocity. Sometimes an object is subject to resistance and friction at the same time. For example, when a car is moving, it is subject to the resistance of air and the rolling friction of its tires Friction sometimes makes objects move, unlike resistance.)

5. Friction is a parallel relationship between objects, a force that can be seen and felt. Gravity is an invisible force that exists in space. Friction is mutual and occurs on the surface of an object. If there is no friction, then it can be understood as a permanent moving object, which is the same kind of parallel relationship. Gravity is a vertical relationship. Gravity is a force manifestation of the earth's magnetic field, which can be regarded as vertical. When the object on the earth's surface loses its balance, it will only fall on the earth's surface from top to bottom.

6. When there is an object moving at a constant speed, the work done by the friction force on the object is the downward component of gravity (the resultant force is 0) f mill. = sin ⊙ mg WF mill = flcosa

7.

On the iPad, you can play the game "sail" through your own browser

is a Chinese mainland children's science fiction community development game developed by Shanghai rice network technology Co., Ltd., which was released in mainland China in June 12, 2009. The game type is web-based game, the main role is Cyril robot and genie, the user group is under 18 years old, and the charging method is partial free (props and other charges)

"the sailor" is a novel with the theme of exploration and elves cultivation, which tells a strange story between sails and elves when they are looking for energy for mankind

extended information:

players can set up their own teams in "sail". Different teams can fight each other. Members must contribute to the team. The team has three areas. According to the level of the team, different functions can be unlocked

in the game, click the achievement category on the left to see the relevant achievement content, and click the sub category achievement icon to unlock the achievement. Each achievement has corresponding achievement points, and each new achievement will add up to your total achievement points. After accumulating a certain amount of achievement points, you can get military ranks of various levels and obtain military rank suits

in the game, the player can only control the game except the spirit fight. Sal can dress up. Sal mainly commands the elves to fight, but he doesn't. A player can only control one sel. The SEL controlled by the player can change its name and skin color at will in the game. Cel has no attribute, no rank and no skill

8. The iPad can be made into a small computer screen. Using the iPad as a monitor can save that part of the screen, and even turn the iPad into a small TV set. When you need to watch TV, you can directly turn on the iPad and connect to the network to watch directly.

9. The two graphics cards are of the same level. Gtx1060 has better gameplay and lower power consumption. Rx580
8g has high performance price ratio and high power consumption. In fact, the performance gap between the two graphics cards is very small, which point can be ignored. In general, gtx1060 is better

10. First, install ace on the computer, and then connect the computer with the data cable on the mobile phone. After opening ace, click Install mobile terminal on the home page