# Friction is electricmagnetic force; why friction is not conserved?

• Haorong Wu
In summary, friction is not a conservative force because it does not satisfy the condition for a force to be conservative. Although most macroscopic forces are a result of electromagnetic interactions, the energy gained from friction does not result in an increase in the macroscopic kinetic energy. While the electromagnetic force can be conservative, other electrodynamic and magnetic forces are not.
Haorong Wu
Obviously, friction is not a result of other three kinds of force, and electricmagnetic force is conserved, then why friction is not conserved?

Energy is always conserved, so that is not relevant. For a force to be conservative it must satisfy ##\oint \vec F \cdot d\vec r = 0## which friction does not.

Forces may be conservative (or not). There is no such thing as "conservation of forces".

If you look at a microscopical picture, indeed most of the macroscopic forces (not just friction) are the result of electromagnetic interactions. But then you have to be consistent with the microscopic view. The result of friction is the increase in the kinetic energy of some molecules but this increase does not result in an increase of the KE of the macroscopic bodies.
So as Dale said, the energy is conserved.
The mechanical, macroscopic energy is not.

Dale and weirdoguy
If you are sitting at the breakfast table and gently push your bowl away from you, you can "feel" the friction, right -- you have to "push"? Now when you pull the bowl back closer to you do you feel the same, or does the bowl seem to be pushing your hands along?

Now compare that to say, picking up a suitcase. You pull on up the handle, the suitcase rises up from the floor. When you let it back down, you feel it pulling down? Or do you have to push it back down?

Haorong Wu said:
Friction is electricmagnetic force; why friction is not conserved?
Did you mean to say "why friction is not a conservative force"?

The electromagnetic force in general is also not conservative.

The electrostatic force (Coulomb's law) is indeed conservative, and you can define a potential energy for it. However, the "electrodynamic" force (e.g. in Faraday's law) is not conservative, neither is the magnetic force in general.

vanhees71 and nasu

## 1. Why is friction considered an electromagnetic force?

Friction is considered an electromagnetic force because it is caused by the interactions between the charged particles on the surface of two objects. These interactions create a force that opposes the motion of the objects and is known as friction.

## 2. How does friction relate to electric and magnetic forces?

Friction is related to electric and magnetic forces because it is caused by the same fundamental forces that govern these interactions. The electromagnetic force is responsible for all interactions between charged particles, including the creation of friction.

## 3. Why is friction not conserved?

Friction is not conserved because it is a dissipative force, meaning it converts mechanical energy into heat. As objects slide against each other, the energy of their motion is converted into heat due to the resistance of friction. This results in a loss of energy and therefore, friction is not conserved.

## 4. Can friction be eliminated?

Friction cannot be completely eliminated, but it can be reduced by using lubricants or by using materials with lower coefficients of friction. However, even in the absence of visible friction, there will always be some level of microscopic friction due to the interactions between charged particles.

## 5. How does friction affect the movement of objects?

Friction affects the movement of objects by creating a resistance force that opposes their motion. This resistance force can slow down or stop the movement of objects, and can also cause them to change direction. Friction is an important factor to consider when studying the motion of objects and is essential for many everyday tasks such as walking and driving.

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