The person standing on the elevator accelerates the movement of the person under force

People due to inertia to maintain a slower speed relative to the elevator "to" move to the left, so by the elevator to the right friction force of the person to the right This sentence means: at the beginning, people stand on the elevator, the elevator begins to accelerate the movement, people due to inertia will have a moment to maintain the original static state, and at this time the elevator has begun to move to the right, then with the elevator as a reference, people are moving to the left, but the result is that people and the elevator accelerate together, the movement method to the right, people are offset by gravity and support, Only the frictional force provides the person's acceleration to the right, so the person is subjected to the frictional force of the elevator against the person's right.

If he accelerates to the right, it means that he is working together to the right in the horizontal direction, and only the force that can provide the force to the right in the horizontal direction is the friction force, so the friction direction is to the right, as for the latter, look at the definition of static friction.

If two objects that are in contact with each other and squeezed each other, and are relatively stationary, if they only have a relative sliding tendency under the action of external forces, but do not slide relatively, the force that prevents them from sliding relative is called "static friction".

I understand this

Take a look at the definition of friction.

To put it simply, the direction of friction is always opposite to the direction of motion or the direction of movement.

Always supported by gravity and the upward side of the elevator floor;

When accelerating upward, the support force is greater than the gravitational force, and the acceleration is upward;

When accelerating the descent, the gravitational force is greater than the supporting force, and the acceleration is downward;

When decelerating and rising, the gravity is greater than the supporting force, and the acceleration is downward;

When decelerating and descending, the support force is greater than the gravitational force, and the acceleration is upward;

When going up and down at a constant velocity, the supporting force is equal to the gravitational force and there is no acceleration.

Choosing a person is rising at a uniform speed, in a state of equilibrium, and the resultant force is 0 gravity, needless to say, there must be, and there is a contrary equal to the size of the horseman, which is the support provided by the elevator ground that the foot is stepping on, so that the resultant force is 0.

If there are other forces, the balance of the two forces just now will be broken, and there will be no uniform velocity, so there will be no other forces. ,7,The force experienced by a person standing in an elevator rising at a constant speed is.

A person standing in an elevator that rises at a constant speed is subjected to (

a. Gravity, support.

b. Gravity and tension.

c. Tension, gravity, support.

d. Pressure, gravity, support.

Ideas for solving the problem. What is the balance of two forces, I don't understand.

We are beginners.

Carry out the force analysis of people, people rise at a constant speed with the elevator, and people are subjected to gravity and the support force of the elevator to people in the vertical direction. In the horizontal direction, there is neither relative motion nor a tendency to relative motion, so it is not affected by friction, so c is correct

Therefore, c

When a person rises at a constant speed with the elevator, the person is only supported by gravity and the dry ladder of the telecommunication hole. It is not affected by friction.

To be subjected to friction must be conditional:

There is relative motion between one or two objects, and only then can there be dynamic friction to produce a slide.

Second, the object has a tendency to move, and only then can there be friction in the static trembling world.

When the motion state of man and elevator is consistent and both move in a straight line at a uniform speed. There is no friction between the person and the elevator.

This question is a force analysis of people, although people rise at a constant speed with the elevator, people remain relatively stationary relative to the elevator

In the vertical direction, people are affected by gravity, so a pressure is put on the elevator, and the elevator is deformed, and there is an upward elastic force to the person, that is, the support force, and the gravity and support force are a pair of balanced forces;

Neither relative motion nor tendency to move in the horizontal direction takes place, so it is not affected by friction

Therefore, option ABC is incorrect, and D is correct;

Therefore, choose D

The correct answer is A, because you are ascending, the relative position is rising, and the gravitational potential energy will of course increase. Moreover, the elevator accelerates upward, and the speed of the person increases, but the mass of the person remains the same, so the kinetic energy also increases. Thus the total mechanical energy increases.

For people, gravity does negative work (the direction of gravity is opposite to the direction of human motion), and supporting force does positive work (the direction of supporting force is the same as the direction of human motion IGN).

Correct answer choice: a

The supported force is positive, and the mechanical energy increases.

Because the vertical upward support force given by the elevator floor is consistent with the direction of elevator movement, and the potential energy of the person itself is relatively increased, the support force is positive and the mechanical energy increases. Therefore a is correct.

Judging A is correct. The other options are bound to be wrong.

The support force does positive work, and the mechanical energy certainly increases. Landlord, the change of mechanical energy depends on the situation of the force other than gravity and the elastic force of the spring, understand?

Mechanical energy does not know what it is talking about You can understand it this way, you are standing on the elevator because of gravity, the support force is facing upward, and the distance is also facing upwards fs is in the same direction. However, the upstairs over there said that the mechanical energy is gravitational potential energy. How can the gravitational potential energy be reduced, isn't the gravitational potential energy the height multiplied by the acceleration?

Isn't it an increase in height that g has not changed? In fact, you are ignoring everything that is manipulated by an electric energy

The gravitational potential energy increases when the human body rises, and the gravitational potential energy belongs to mechanical energy. So choose A

The teacher said that the friction force must be tangent to the contact surface, and when a person stands upright on the elevator, the friction force must be horizontal, left or right. Then the force analysis of the person shows that in addition to gravity and support, the friction force can only be to the right if the acceleration is to the right. There are two ways to analyze the direction of the force, first, when the motion is clear, according to the relative motion or trend, and second, with the state of motion, the force analysis.

The acceleration is oblique to the right, and the friction force is to the right.

Relative direction of motion, to see the relative motion between the objects in relative motion, both to see the relative motion of the elevator and the human world, because the elevator accelerates to the right, people due to inertia to maintain a slower speed relative to the elevator "to" move to the left, so by the elevator to the right friction of the person.

The questions you ask are actually a reason, your concept is not well mastered, it is recommended that you go back and re-read all the basic concepts in this part, you will know the reason after reading it, many people have asked the same question in the third year of high school, in fact, they only pay attention to the question, but forget to review the basic concepts, this is a taboo, especially those who can't figure it out, basically caused by the forgetting of concepts.