The person standing in the elevator during the accelerated ascent of the elevator

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

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.

The force analysis of the person, the person rises with the elevator at a constant speed, and the person in the vertical direction is subject to gravity and the elevator support force for the person, and these two forces are a pair of balanced forces; 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

The person in the elevator ascending at a constant speed is subjected to the support force and the gravitational force, which balances each other.

Summary. Hello, in the ascent stage, when the elevator starts from a stationary state, the person is in an overweight state, and the pressure of the person on the floor is greater than gravity; When the elevator moves at a constant speed, the resultant force on the person is zero, and the pressure on the floor is equal to gravity. When a certain floor is about to be reached, the elevator rises with uniform deceleration, the person is in a weightless state, and the pressure of the person on the floor is less than the gravity of the person until the elevator is stationary, and the pressure of the person on the elevator floor is equal to the gravity of the person.

There is an object in the elevator, when f

Hello, in the ascent stage, when the elevator starts to move from the state of static spike difference, the person is in an overweight state, and the pressure on the floor is greater than the gravity; When the elevator moves at a constant speed, the resultant force on the person is zero, and the pressure on the floor is equal to gravity. When the hail is about to reach a certain floor, the elevator decelerates and rises evenly, and the person is in a weightless state, and the pressure of the person on the floor is less than the gravity of the person, until the elevator is stationary, and the pressure of the person on the elevator floor is equal to the gravity of the person.

The ground Zheng Bureau continues to decline, and it is getting farther and farther away from people, indicating that the ground is moving, and the position of the ground and people or elevators has changed, so people or elevators are used as references.

So the answer is: elevators

Answer]: When the bucket finger accelerates up or decelerates down, the acceleration is upward, and the object is in an overweight state. The air start is in an overweight state when the elevator starts upwards.

The middle period is at a constant speed, so it is in a normal state. When the elevator accelerates down or decelerates up, its acceleration is downward, and the objects are in a state of weightlessness. When the elevator finally stopped, it was in a state of weightlessness.

Therefore, choose B.

Summary. When the elevator rises, each corresponding point of the elevator moves upwards at the same distance, which belongs to the translational phenomenon.

When the elevator rises, each corresponding point of the elevator moves upwards at the same distance, which belongs to the translational phenomenon.

My consciousness can be expressed as"Mathematical phenomena"Nope"

No, the elevator ascent is a translational phenomenon, not a mathematical phenomenon.

The accelerated ascent is in an overweight state, so fn mg mA