Does the force that does not do work during the movement have an impulse

The force does not do work, it can only be said that this force does not accumulate in space, but it does not prevent it from accumulating in time, so as long as this force is not zero and time is not zero, then this force has impulse.

A pair of internal forces are equal in magnitude and opposite in direction, but they act on two particles respectively. They may all do positive work, they may all do negative work, they may all do positive work, they may not do any work, they may not do work. The values of the work done by each may also be different, because the displacement of the two particles may be different.

For example, if a person is wearing skates and standing by a wall, and then the person pushes the wall, the person will move, and in this process, the person's work on the strong is 0, because the wall is not moving. The work that the wall does to people is positive. So the total merit is positive.

For another example, if two magnets are placed on a smooth horizontal plane, with the poles of different names facing each other, and then the magnets are pushed in opposite directions, the attraction of each of them will be negative in the course of the subsequent movement. So the total merit is negative. Let's take another example of not doing work.

If two people tug of war, but neither pulls the other, then the internal force between them will not work. The total work is 0In summary, the internal forces can change the kinetic energy of the particle system.

The force does not do work, it can only be said that this force does not accumulate in space, but it may accumulate in time, and there is impulse.

No, the impulse is the effect of the accumulation of force in time, and the work is the effect of the accumulation of force in space, that is, the effect of force, and it lasts for a period of time, regardless of whether the object is moving or not, must produce an impulse. Work requires a certain displacement of the object in the direction of the coded force.

The supporting force is equal to the gravitational force and also has an impulse where the total impulse of the whole object is zero.

Impulse i=ft Although the gravitational force has a net force of 0 in the vertical direction, there is no displacement. However, according to the definition of impulse, impulse is only related to the force and the duration of action. And gravity isn't missing during movement, is it?

Impulse refers to the amount of change in momentum, and the object of impulse is an object, not a force, so the statement that the impulse of a force is zero is simply false.

You can say that the impulse of an object is zero, but don't say that the impulse of a force is zero.

Impulse-defined ft is obviously not related to work done.

As for the conceptual explanation, the direction can be changed even without work (kinetic energy does not change), do not forget that velocity is a vector (e.g. the effect of the Lorentz force).

The work done is 0 may be the same before and after, the total work is 0, one is fs and the other is -fs, so there is a time difference before and after is also powerful, according to the impulse calculation formula, it can be known that it is not 0

The work done by force is the accumulation of the effect of force in space, from the formula point of view, it is w=fx, if the object is acted by the force, but there is no displacement in the direction of the force, that is, x=0, then w=0, at this time, the force does not do work in that period of time. That's the first half of the sentence.

However, the impulse is the accumulation of the effect of force in time, from the formula it is i=ft, as long as the object is subjected to the force for a period of time, there will be impulse, which is the meaning of the second half of the sentence.

One. Momentum and impulse.

1.Momentum. By definition, the product of the mass and velocity of an object is called momentum: p=mv

Momentum is a state quantity that describes the state of motion of an object, and it corresponds to the moment.

Momentum is a vector quantity, and it has the same direction as velocity.

2.Impulse. By definition, the product of the force and the time of action of the force is called the impulse: i=ft

Impulse is a physical quantity that describes the time-cumulative effect of a force and is a process quantity, which corresponds to time.

The impulse is a vector quantity, and its direction is determined by the direction of the force (it cannot be said to be the same as the direction of the force). If the direction of the force remains constant for the duration of the action, then the direction of the impulse is the same as the direction of the force.

In high school, it is only required to be able to calculate the impulse of a constant force using i=ft. For the impulse of variable force, the momentum theorem can only be found by the change in momentum of an object at the high school level.

It is important to note that impulse and work are different. Constant force may not do work for a period of time, but there must be impulse. mh

Example 1What is the impulse of gravity, elastic force and resultant force in the process of sliding from the top of a smooth inclined plane with a height of h to the bottom without initial velocity?

Solution: The force acts for the same amount of time.

The magnitude of the force is mg, in that order

mgcos and mgsin, so their impulses are, in order:

In particular, it should be noted that although the elastic force does not do work in this process, it has an impulse on the object.

2. The momentum theorem.

1.Momentum theorem.

The impulse of the resultant external force on the object is equal to the change in momentum of the object. i=δp

The momentum theorem states that impulse is what makes the momentum of an object change, and impulse is a measure of the change in the momentum of an object. The impulse in question must be the impulse of the resultant external force on the object (or the vector sum of the impulses of the various external forces on the object).

The momentum theorem gives a relationship between impulse (process quantity) and momentum change (state quantity).

Modern physics defines force as the rate of change in the momentum of an object:

form of momentum of Newton's second law).

The expression of the momentum theorem is vector. In the case of one dimension, the individual vectors must be positive in the same specified direction.

Example 2What is the change in the momentum of an object with mass m in t seconds after throwing an object with initial velocity v0?

Solution: Since the resultant external force is the gravitational force, δp=ft=mgt

With the momentum theorem, there are two alternative equivalent methods for finding both the impulse of the resultant force and the change in the momentum of an object. It is much more convenient to solve this problem with impulse than to find the vector difference between the end momentum and then the beginning and end momentum. When the resultant external force is a constant force, it is often simpler to use ft; When the resultant external force is a variable force, it can only be found by δp in high school.

Yes, impulse = f*t, as long as there is a strong presence and there is time there is impulse, just no work is done.

There should be ... Impulse is a state quantity, and gravity will have an impulse as long as it exists...

Yes, the impulse of the resultant external force is equal to the change in momentum.

As long as there is force and there is a time of action, then the impulse is not zero!

The relationship between impulse and work residue:

Impulse i=ft, work w=fs

Time t is an absolute existence and cannot be 0, so there must be an impulse if there is a bright hail force. S can be 0 or not, and we don't know if it exists or not.

Therefore, active work is like a key hole must have impulse, but impulse does not necessarily have active power.

Relationship between momentum and kinetic energy:

Momentum = mv, kinetic energy = m multiplied by v squared in divided by 2.

So: the square of momentum.

2m multiplied by kinetic energy.

The book says that this formula should be memorized, but in fact, it is to omit 1 step to solve the problem, so you don't have to force it if you can't remember it).

Never mind. Impulse is the cumulative amount of time that a force acts on an object.

Even if the object does not move, there is impulse.

But there is no work.