Question of kinetic energy vs momentum, what is the relationship between momentum and kinetic energy

I think what you said is wrong.

Momentum must be conserved when kinetic energy is conserved" is false. For example, if an object moves in a uniform circular motion, the kinetic energy does not change, and the momentum is changed (direction).

The conservation of kinetic energy is that the sum of all the forces doing the work is 0 (for a single object, the work done by the combined external force is 0). The resultant external force can not be 0, but it is always perpendicular to the direction of velocity and does not do work.

Momentum is conserved between and impulse, and the resultant force multiplied by time is the impulse.

In general relativity, kinetic energy is a component of four-dimensional momentum, and you can appreciate this.

Since there is a resultant force and time, the momentum needs to change, and the kinetic energy also needs to be displaced.

The law of conservation of momentum is a universal theorem of nature and holds true in both classical Newtonian mechanics and modern quantum mechanics, while conservation of kinetic energy is only a category of Newtonian mechanics.

For what you said, I think you are mistaken, it must be when momentum is conserved, kinetic energy must be conserved, because momentum is a vector quantity, and kinetic energy is a scalar quantity. There are more particles where kinetic energy is conserved and momentum is not conserved, and uniform circular motion is one.

Momentum does not necessarily and also does not change when kinetic energy is kept in equilibrium because momentum is a vector quantity while kinetic energy is a scalar quantity.

It seems that kinetic energy has little to do with momentum.

You are right that the conservation of kinetic energy has nothing to do with the conservation of momentum.

But because momentum is a vector and kinetic energy is a scalar quantity, then the kinetic energy of an object changes, its momentum must change.

But when the momentum of an object changes, its kinetic energy does not necessarily change.

Counter-example: When the velocity of the object becomes an equal-large reversal).

The law of conservation of momentum is a universal law of nature and has nothing to do with whether kinetic energy is conserved or not. In general application, conservation of kinetic energy refers to the fact that there is a physical process (such as a collision) in which no kinetic energy is converted into other forms of energy (such as internal energy). If not, the kinetic energy is conserved; If there is, the total kinetic energy of the system is reduced.

The situation you describe is known by the kinetic energy theorem and is also true, but only to study a single object. Conservation of kinetic energy is generally for the system.

Relationship between momentum and kinetic energy: Both momentum and kinetic energy are related to the mass and velocity of an object. They describe the properties of moving objects from different perspectives, and there is a relationship between the size of the two: p2 2mek.

Difference Between Momentum and Kinetic Energy

1. The magnitude of momentum is proportional to the magnitude of velocity. The magnitude of kinetic energy is directly proportional to the magnitude of the velocity squared. That is, objects with the same momentum but different masses have different kinetic energy, and objects with the same kinetic energy but different masses have different momentum.

2. Momentum is a vector quantity, while kinetic energy is a scalar quantity. Therefore, when the momentum of an object changes, its kinetic energy does not necessarily change, whereas when the kinetic energy of an object changes, its momentum must change.

3. Since momentum is a vector, the cause of momentum change is also vector, that is, the impulse of the object subjected to an external force; Kinetic energy is a scalar quantity, and the reason for the change in kinetic energy is also a scalar quantity, i.e., an external force doing work on an object.

4. "Momentum" and "kinetic energy" are both physical quantities used to describe the amount of motion of an object when it is doing "mechanical motion". But the angle of the two descriptions is not the same. "Momentum" describes the motion of the object directly from the perspective of mechanical motion mechanics, that is, it describes the magnitude of the object's motion and also describes the direction of motion.

The formula for the relationship between momentum and kinetic energy is: p 2 = 2mek.

In physics, momentum is a physical quantity related to the mass and velocity of an object. In classical mechanics, momentum (kg·m s in the International System of Units) is expressed as the product of the mass and velocity of an object.

Physics is the study of the most general laws of the motion of matter and the basic structure of matter.

As a leading discipline in the natural sciences, physics studies the most basic forms and laws of motion of all matter, from the universe to elementary particles, so it has become the research foundation of other natural science disciplines.

First sentence. Wrong.

Because momentum has a direction, such as v1=6m s, v2=-6m s, the momentum changes, and the kinetic energy does not change.

Second sentence. Leaks with a nano belt.

Because the kinetic energy changes, the magnitude of the velocity must change, so the momentum must change.

The third sentence. Wrong.

The example is the same as in the first sentence. The momentum changes, but the velocity does not change, because the velocity is the magnitude of the velocity. No directions.

Fourth sentence. Wrong.

Because the external force does the work and the grasp = the kinetic energy changes, the momentum changes.

Kinetic energy does not necessarily change, so it does not necessarily do work with external forces.

Is it full of holes???

There is a formula relationship: ft=mv end mv beginning.

Momentum, MV vector, impulse, ft, the product of force and time, which is used to measure the increment of momentum. It is a vector quantity, that is, it has a direction, so the impulse and momentum need to be put together, that is, the impulse of the external force of the object is equal to the increment of the momentum of the object. This is what we call the momentum theorem, which is ft=mv at the end of mv and mv at the beginning.

or ft = mδv) kinetic energy, 1 2m v squared, scalar. All energy has no direction, it is just a state quantity, and it has instantaneous side-response to the wisdom of luck. The kinetic energy theorem generally deals only with the initial and final states of motion.

Kinetic energy is the energy possessed by the motion of an object. It belongs to a kind of energy. So it conforms to the law of conservation of energy.

If he is a scalar quantity, then he has only size and no direction.

In high school, you just need to remember that moving objects fit these formulas. When doing the problem, determine which formula to apply by analyzing the process of motion and the relationship between the known quantity and the required unknown quantity, and then form an equation to find the unknown or indirect quantity you require. For example, in relation to time, the theorem of momentum, impulse, and momentum is applied.

There is no time or energy related to gravitational potential energy, or only the kinetic energy theorem that deals with the initial and final states of a moving object.

When objects collide, if the equation of conservation of kinetic energy is used, it is not necessarily correct, because kinetic energy will be converted into other energy, such as gravitational potential energy, elastic potential energy. If two objects collide on a smooth horizontal plane, the action time of the two objects is extremely short, and the internal force is greater than the external force, which can be regarded as the momentum is conserved.

The energy that an object has due to its motion is known as the kinetic energy of the object. Its size is defined as one-half of the product of the mass of the object and the square of the velocity.

Therefore, the greater the velocity of an object of the same mass, the greater its kinetic energy; The greater the mass of an object moving at the same velocity, the greater the kinetic energy it has.

The kinetic energy is the standard early selling volume, no direction, only size, and cannot be less than zero. Kinetic energy is consistent with work and can be directly added or subtracted.

The kinetic energy is a relative quantity, and v in the equation is related to the selection of the reference frame, and the kinetic energy of the object is different in different reference frames, and v is different.

Momentum is the cumulative effect of force on time and corresponds to force multiplication time; Kinetic energy is the cumulative effect of force on space and corresponds to the force multiplied by distance.

Similarities:

Both are physical quantities that describe the state of motion of an object.

It's all about m and v.

Differences:

Momentum is only a table for the transmission of motion. Kinetic energy can be both transferred and transformed.

Momentum is a vector quantity, and the change in momentum is associated with f, t. Kinetic energy is a scalar quantity, and the change in kinetic energy is associated with work.

When the kinetic energy changes, the momentum must change. While momentum changes, kinetic energy does not necessarily change.

The physical definition of kinetic energy is the work done to move an object from a state of rest to a state of motion. In classical mechanics, it is e=(1 2)mv 2

Just looking at the definitions, these two goods are of course different, and they are very different. In addition to their values, they are all related to quality and speed.

However, in practical application and problem solving, these two relationships are relatively close (I guess you are asking about the difference between conservation of kinetic energy and conservation of energy).

Consider the following question, where one car collides with another. Knowing the speed and mass of the two cars, I would like to know their trajectory after the crash.

Apparently, at the moment of the crash, the two cars collided with each other and sparks flew up. I don't know how much energy has become internal energy, and it is definitely not feasible to use the conservation rate of energy at this time. But thankfully, the conservation of momentum can still be used.

And in this case, there is a stronger reason to use the conservation of momentum - in momentum velocity is a vector, which means you can even know the direction in which they collided! In such energy-losing collisions, the so-called "inelastic collisions", it is very unwise to apply the equation of energy conservation.

Understand the formulas of kinetic energy and momentum.

Kinetic energy = 1 2mV2 , is a scalar quantity.

Momentum = mv, which is a vector and v is directional.

If there is kinetic energy, then v is not zero, and momentum must not be zero.

The imitation body of the object grip beam with momentum must have kinetic energy, but the kinetic energy of the momentum change is not the same, for example, the momentum is changing in a uniform circular motion, and the momentum is changing all the time but the kinetic energy is unchanged.

I don't know where your words come from, I hope the wrong Duan Xian words can be corrected.