It can still move because of zero force on the object

The landlord should distinguish the force from the force of the object and the motion.

When an object is in motion.

Zero by the combined external force -- physical rest or doing uniform linear motion.

The resultant external force is not zero--- the object moves in a uniform and accelerated linear motion.

So when the resultant force is zero.

An object may be stationary, but it can also move in a straight line at a uniform speed.

It is impossible to lift a heavy object when using a force of gravity on the ground.

At the moment of lifting, the external force must be greater than the gravitational force of the object.

In the process of ascent, if it rises at a uniform velocity, the external force is equal to the gravitational force (in which case the net force is zero).

Why can a force of gravity on an object lift an object from the ground but not lift an object?

Force is the amount that changes the state of motion of an object, and the state of motion of an object with zero force will not change, while there are two kinds of states of an object, one is stationary and the other is a uniform linear motion, which should be the second type just now.

When you lift an object with force, the object is supported by the gravitational ground and your pulling force, accelerating upwards. When leaving the ground, it loses support and maintains a constant upward speed.

An object cannot be lifted from the ground with a force of gravity of the object.

It can be lifted because the force used in a very short period of time is greater than that of the object, and the object accelerates upward, and then the force recovers to the same weight as the object in a very short time, and moves at a uniform speed.

Due to the extremely short time period, this is an illusion brought about by the experience of everyday life.

If the resultant force is zero, it may be in the state of an object moving at a uniform speed, and the second is at rest, which is a constant motion, because the object is already in a state of motion, and the object has inertia.

He can be moving in a straight line at a uniform speed, subject to a pair of balanced forces, and the resultant force is zero.

For example, if there is a circular motion with a uniform velocity, the velocity is constant, and the object is subjected to centripetal force.

Velocity is the ratio of distance to time, and velocity is the ratio of displacement to time; Velocity is a vector quantity, with magnitude and direction, which describes the speed of the object's motion and reflects the direction of the object's motion; The velocity is a scalar quantity, and there is a size but no direction.

In order to accurately describe the speed of the object's motion, take a very short period of time δt, and if δt is very, very small, then it can be assumed that δx δt (displacement ratio time) represents the velocity of the object at time t, which is instantaneous velocity. Instantaneous velocity is a vector quantity, which is the ratio of displacement to time, and has a direction (the direction of the object's motion), and the magnitude of the instantaneous velocity is the velocity, which can also be called the instantaneous velocity.

Since the speed of curvilinear motion must change, at least its direction is always changing, the medium velocity of the object moving in a curvilinear motion must not be zero, the resultant external force must not be zero, and there must be acceleration. (Note: There are only two states in which the resultant external force is zero:

Stationary and uniform linear motion. ）

If the direction of the speed of the curved motion must change, the curvilinear motion must be a variable speed motion, and vice versa, the variable speed motion is not necessarily a curved motion.

That's not right! Two scenarios.

The kinetic energy of an object moving at a uniform velocity does not change, but the resultant external force on it is 0

Think about the Lorentz force again, the electron moves quietly in a uniform circle in a uniform magnetic field, and is subjected to the resistance and Lorentz force, the resultant external force is not 0, and the kinetic energy remains unchanged.

In summary: if the kinetic energy of a moving object remains unchanged, the net force experienced by the object is not necessarily zero of the Qi Mu bond.

An object that is stationary or moving in a straight line at a uniform speed may not be subjected to a force or that the resultant external force is zero, because the object is stationary or moving in a straight line at a uniform speed is a state of equilibrium, that is, the object remains in its original state, and the original state is still the same.

However, if the external force is not zero, the force on the object will change the shape and motion state of the Zen people, and it will not be stationary or uniform motion.

It can only be said that the object is stationary or moving in a straight line at a uniform speed, and if the force is applied, then the sum of the external forces is set at zero.

Possible. Analysis: According to the formula p=fxcos, where is the angle between the resultant external force and the direction of motion of the object, f is the resultant external force, and x is the distance of the object; Therefore, as long as the angle between the direction of the resultant external force and the direction of motion of the object is at a right angle, then the resultant external force will only change the direction of motion of the object and do not do work.

It is entirely possible that the condition for the work to be done is that a displacement is produced in the direction of the force. So as long as there is no displacement in the direction of the force, the work done is 0. Typically, a person walks on a horizontal plane holding something, and is forceful but ineffective on the object.

The answer is b, direct method: because f is ≠ 0, so f is combined * t = p≠0 elimination method: when f is always perpendicular to the initial velocity, then the object is doing a uniform circular motion, and the kinetic energy is always unchanged at this time, so a is wrong.

And when the f conjunction is constant, from the f conjunction = m*a, it can be seen that the acceleration is also constant, so c is wrong when the direction of f conjunction and the direction of the initial velocity are in the same straight line, and the direction of velocity is unchanged, so d is wrong.

If it is said that the uniform circular motion is that the external force is not zero, the kinetic energy is unchanged, A is wrong, B is right, the velocity direction of the object in C is uncertain, if the speed direction of the linear motion of uniform acceleration is unchanged, the deceleration will change, and the acceleration will not change, so, choose D, by the way, it is not easy for the mobile phone to play.

d The velocity of the object must change in direction.

The external effect of an object not being subjected to an external force (or not being subjected to an external force in a certain coordinate direction) and the net force being zero (or projected to zero in a certain coordinate direction) are the same: the object remains stationary or moves at a uniform speed; However, the internal effects are different, the former has zero internal forces of the object, and the latter causes the internal forces of the object, such as: shear force, tensile (compressive) force, bending moment, torque, etc., which is fully reflected in ,-- "mechanics of materials".

Furthermore, if it is a uniform motion, the former has no external force to do the work, but the latter part (or all) of the force is work, but the work of the resultant force is zero.

The "force" mentioned above includes the "force couple moment".

The resultant force is zero, and it can also be a balancing force.

Equilibrium state: The state in which the object is relatively stationary with the ground, moving in a straight line at a uniform speed or rotating at a uniform speed is called the equilibrium state of the object, referred to as the equilibrium of the object.

For an object to be in equilibrium, the following two conditions must be met:

1. Under the action of the common point force, the net force of the object is zero, that is, the acceleration a=0;

2. The resultant moment of the object should be zero, that is, the angular acceleration is equal to 0 (this is the so-called rotational equilibrium).

As long as the above two conditions are met, the object is in equilibrium regardless of whether it is in motion or not.

Or in a state of constant motion.

It is also possible to do fixed-axis rotation.