High school teacher, please come in! 50, high school teacher please come in!

Temperament. The background and knowledge are all gaps, and you don't know it even if you are a teacher.

A good student does not lie in how good he or she learns, but in whether he is conscious. Self-conscious children will always have results, and they will also find teachers to like. The fundamental difference between different schools lies in the strength of teachers. A good teacher can even turn a poor student into an excellent student.

1.There is no gap, because their results are all earned through their own efforts. The same is an educated student.

2.If you want to say, it should be that the education methods received will vary from person to person, such as temperament, quality, knowledge, and heritage can be learned. As long as you have the determination to learn. Anonymity.

In good schools, top students are passive, infected, or implicated; In a poor school, the top students are active, they want to study well on their own, be admitted to a good school, and escape from this poor school.

If you want students to have good grades, you need to have good teachers, be able to integrate with students, and understand students. It is not difficult to see that the relationship between teachers and students is particularly good in the subject with good grades.

The revenge is different, the self-motivation is different, and the students in the poor school can't realize that "there is a sky outside the sky, and there are people outside the world"! Even their future ideals will not be at the same level.

If the acceleration to the right is greater than this value, the small block will slide upwards, and if it is less than that, it will still slide downwards.

If the kinetic friction factor of the inclined plane is a, the gravitational force on the small block is orthogonally decomposed in two directions, parallel to the inclined downward (G1) and perpendicular to the inclined downward (G2).

g1=mgsinσ

g2=mgcosσ

Let the acceleration of the inclined side to the right be a, then the small block is equivalent to being subjected to a right-left force f=ma, and this force is orthogonally decomposed along the upward (f1) parallel to the inclined (f1) and perpendicular to the downward (f2) inclined plane, there is:

f1=fcosσ=macosσ

f2=fsinσ=masinσ

Friction: f=a(g2+f2)=a(mgcos + masin) Since the block remains relatively stationary with the inclined plane in the case of acceleration a, the value of the above equation (magnitude of friction) is 0, so

a(mgcosσ+masinσ)=0

amasinσ=-amgcosσ

a=-gcotσ

There is nothing wrong with the first question, if the acceleration increases, it moves upwards, and when the acceleration decreases, it moves downwards.

The answer to the second question on the first floor is correct, but the analysis at the end is problematic, because the last is to say that it is relatively stationary, but it is not that the friction is 0, there can be static friction, so the final friction is a range, that is, the maximum static friction along the inclined upward and the maximum static friction downward, in this case, the final acceleration to the right is a range, and theoretically there is an acceleration to the left.

First of all, I am not a teacher, but I think this question is very simple.

There must be friction between the wooden blocks.

Let there be three wooden blocks, from top to bottom: a, b, c. where c is in contact with the horizontal plane.

When the horizontal force (set to the right) acts on B, and B is above A, then A will have a tendency to move to the left relative to B, then A will be subjected to a rightward static friction force (because there is no relative motion between AB, only the tendency to move, so it is a static friction force. Whereas, the direction of friction is generally the opposite direction of the direction of the direction of motion. ) to stop this movement trend.

A is subjected to only one frictional force).

c is below b and is in contact with the horizontal plane. Same as above, B will move to the right with respect to C, so C will give B a leftward static friction. And the action of force is mutual, so c will be subjected to a frictional force to the right by b.

And because "there is friction in the horizontal plane", C is subjected to the rightward friction of B, and it will move to the right relative to the horizontal plane, so the horizontal plane will give C a leftward friction force to stop C's movement. (c is subjected to two frictional forces).

Friction is all about blocking"Movement (kinetic friction) that has taken place"or"Will (note is: will. That is, there is no relative motion, but there is a tendency to occur"。

I don't know how to think about it, as long as I work hard, I will always understand that day again.

B should be in the middle. So suppose A is the top piece, and since the three objects are at rest, A is not subject to friction. b is subjected to the static friction force of c on it, which is in the opposite direction to the horizontal force and is equal in magnitude.

c is subjected to the static friction force of b on it, and the direction is the same as the horizontal force, and the magnitude is equal; c is also subjected to the static friction of the horizontal plane, in the opposite direction to the static friction of b against it, and the magnitude is equal.

First of all, I think A is the top, B is the middle, and C is the bottom. Then a is only subject to the force of its own weight. Friction is related to mass and is related to the area of force.

Three identical pieces of wood stacked on top of each other, then a is the least effective. The frictional force of b by the sum of the gravitational forces of itself and a c is subject to the frictional force of 3, but this is static friction. If the analysis is wrong, please don't laugh at it, I haven't touched this field for more than 10 years.

A is only subjected to gravity in the vertical direction and B is supported by A.

The vertical direction of B is subject to gravity, the support force of C to B, and the pressure of A to B; The horizontal direction is subjected to a horizontal force to the right and a static friction force to the left, equal to f, c to b.

C is subjected to gravity in the vertical direction, the support force of the ground on C, and the pressure of B on C; The horizontal direction is subjected to the static friction of B to C on the right, equal to f, and to the left, equal to f, the static friction of the ground to C.

Big brother, you didn't even say how A, B, and C were placed.