Non-Fundamental Forces

[Baron Opal II]

Whilst in contemplation, I thought upon the four fundamental forces: gravity, electromagnetism, nuclear, and decay. There is some discussion as to gravity's place on this list, and perhaps a fifth that should be there. As I considered these things, I thought "what are non-fundamental forces?"

I suppose the division of electric and magnetic fields would be one. Kinetic force as a sub-division of gravity, perhaps. But I haven't come across a list of these, and wonder if anyone knows of such?

 

[Tonguez]

The Non-Fundamental Forces arise as the result of Fundamental Force affecting particles/matter

Repulsion Force is the classic 'Force Wall effect' that prevents objects from passing through it. It’s the result of electromagnetic forces repelling each other when in close contact.

Kinetic Friction is the resistance that surfaces encounter when moving over each other. It is also an emergent effect of electromagnetic interactions between atoms.

Adhesion Force is part of electromagnetic interaction that causes objects to cling to each other and is thus the opposite of Repulsion

This is also seen in Tension Force transmitted along an object as the electromagnetic forces within the material resist stretching or compression returning the object back to its original state.

Buoyant Force is created as a result of gravity acting on fluid molecules, creating a pressure gradient that asserts an upward force on an object submerged in the fluid

Centripetal Force is a result of gravity or tension keeping an object moving in a circular path

 

[Umbran]

Whilst in contemplation, I thought upon the four fundamental forces: gravity, electromagnetism, nuclear, and decay.

Because I am a physicist, I must.

The "four fundamental forces" are gravity, electromagnetism, the strong interaction (aka "the strong nuclear force") , and the weak interaction (aka "the weak nuclear force").

"Decay" is not a fundamental force.

 

[Umbran]

Kinetic Friction is the resistance that surfaces encounter when moving over each other. It is also an emergent effect of electromagnetic interactions between atoms.

In fact, almost every force you see in everyday human life is some variety of electromagnetic or gravitic interaction. Other than the fusion power of the sun, the strong and weak interactions play very little part in our macroscopic experiences.

This is also seen in Tension Force transmitted along an object as the electromagnetic forces within the material resist stretching or compression returning the object back to its original state.

If you want to think of it that way, there's actually a trio - Tension, Compression, and Shear.

 

[Umbran]

There are four fictitious forces (also sometimes called "pseudo forces") that seem to act on objects in accelerating frames of reference.

One is in the case of any linear acceleration relative to the origin - the "force" that pushes you back in your seat when a car accelerates.
One is the centrifugal/centripetal force
One is the Coriolis effect
One is the Euler force, when you have a variable rate of rotation (as in - when a merry-go-round speeds up, you feel a push towards the back of your horse - that's the Euler force).

 

[Tonguez]

In fact, almost every force you see in everyday human life is some variety of electromagnetic or gravitic interaction. Other than the fusion power of the sun, the strong and weak interactions play very little part in our macroscopic experiences.

If you want to think of it that way, there's actually a trio - Tension, Compression, and Shear.

Yeah I only did High School Physics and the stuff I have up there is from creating Super Heroes - I like to have the powers at least theoretically based in science and have noticed that most everything is electromagnetic interactions. Superheroes manipulating nuclear interactions tend to come off as doing magic more than anything else to us mere mortals

Anyway do you mind telling us what you actually - practically - do as a working physicist? It might make for some good inspiration

 

[Paul Farquhar]

I'm a working physicist. I teach physics in high school! Umbran gives an excellent explanation, so I won't add anything.

 

[Baron Opal II]

Because I am a physicist, I must.

The "four fundamental forces" are gravity, electromagnetism, the strong interaction (aka "the strong nuclear force") , and the weak interaction (aka "the weak nuclear force").

"Decay" is not a fundamental force.

I was hoping you and the other local physicists would provide your insights.

Interesting, I've seen the weak force referred to as decay or nuclear decay. I stand corrected. I certainly wasn't talking about organic decay and the like.

In fact, almost every force you see in everyday human life is some variety of electromagnetic or gravitic interaction. Other than the fusion power of the sun, the strong and weak interactions play very little part in our macroscopic experiences.

That's what I thought. I was trying to think of some practical application of Strong or Weak force and didn't come up with much. Mainly what I could think of is possibly speed up nuclear decay to get lead more quickly or a modulate the strong force to make super-heavy elements.

 

[Paul Farquhar]

Interesting, I've seen the weak force referred to as decay or nuclear decay. I stand corrected.

Whist I have never heard that, the weak and strong nuclear forces (along with electromagnetism) govern radioactive decay. So I suppose that is an attempt to explain something that otherwise has no discernible effect on the human scale.

Decay, of course, isn't a force, or even a pseudo force. A pseudo force is still measured in newtons and can be treated as a force in certain calculations.

The Coriolis force is a good one to explain what we mean. Normally, when doing sciency calculations, we treat the ground as if it were stationary. But of course this isn't true - it's on a rotating sphere. Rather than trying to redo all your calculations taking rotation and position on the Earth's surface into account, you can model the effect as an additional pseudo force. This is what causes hurricanes to spin one way in the northern hemisphere, and the opposite way in the Southern.

 

[Umbran]

Interesting, I've seen the weak force referred to as decay or nuclear decay. I stand corrected.

So, as already noted, most of the physical interactions we experience are really electromagnetic interactions between atoms and molecules. Therefore, if you smack a china cup on the counter, it breaking is, under the covers, electromagnetic forces.

Would you then call the electromagnetic force the "breaking force"? No.

Same with the Weak interaction. Yes, it is involved in many/most radioactive decays. But it is also involved in most nuclei holding together, too. There is no dynamic action to observe then, though, so there isn't much to talk about or learn from it.

That's what I thought. I was trying to think of some practical application of Strong or Weak force and didn't come up with much.

Well, the Strong force has a range of about 10^-15 meters, and the Weak about 10^-18 meters. The interactions happen between or within subatomic particles. Kind of hard to have a human-practical application at that range.