Can Fundamental Yanks Replace Forces in Physics?

[beans]

So I was thinking physical a while back and I came up with some conceptual conundrums and I was hoping some fine folk can help me sort it out.

So to change a particle's position, we must apply momentum. For this to be done we must apply a force. and for this, a yank and so on. My question is, how is that we can move the object if we must first change this infinite time derivative of momentum before anything else? and why is force the most important of these? i.e. why are there fundamental forces rather than fundamental yanks?

Another problem: my brain is telling me that torque defies conservation of energy. If you spin an object with some force near its edge, move closer to the point of pivot and absorb the force from there aren't you getting more force than what you put in?

 

[Pythagorean]

So I was thinking physical a while back and I came up with some conceptual conundrums and I was hoping some fine folk can help me sort it out.

So to change a particle's position, we must apply momentum. For this to be done we must apply a force. and for this, a yank and so on. My question is, how is that we can move the object if we must first change this infinite time derivative of momentum before anything else? and why is force the most important of these? i.e. why are there fundamental forces rather than fundamental yanks?

I've always kind of had an issue with this too. There are infinite derivative involved in motion in the classical regime. But we know that this a result of continuity, and continuity doesn't hold in QM (well, not in the same way). So it seems like it's a misleading consequence of classical mechanics, but this is conjecture.

Another problem: my brain is telling me that torque defies conservation of energy. If you spin an object with some force near its edge, move closer to the point of pivot and absorb the force from there aren't you getting more force than what you put in?

yes, but energy is still conserved. You have to move the smaller forcer over a greater distance to move the bigger force a small distance. And energy is (to simplify the discussion) Force times distance. It will always work out such that force*distance will be the same value for a fixed pivot point.

(note this is not the same force*distance as for torque. That distance is distance from the pivot point. We're talking about distance moved. So if you use a lever to move a rock, you have to swing your end down a long ways to move the rock a little ways.) The forces are pretty much the same, but defined in different directions.

 

[bp_psy]

So to change a particle's position, we must apply momentum. For this to be done we must apply a force. and for this, a yank and so on.

Momentum(p=mv) is something a particle not something that is applied on it. In order to change the particle's position you must you must apply a force on the particle so that you change its momentum. Force is the time rate of change of momentum (F=ma=m(dv/dt)=dp/dt). the bigger the force the faster you can change the particles momentum.

My question is, how is that we can move the object if we must first change this infinite time derivative of momentum before anything else?

There isn't such a thing as an infinite time rate of change of momentum, that is there is no infinite force.There also isn't any such thing as an infinite jerk because force and the time rate of force must be finite.

Another problem: my brain is telling me that torque defies conservation of energy. If you spin an object with some force near its edge, move closer to the point of pivot and absorb the force from there aren't you getting more force than what you put in?

The force is not the same but the energy is conserved.You apply the outer force on a longer distance then that on which the inner force is applied.Since W=F x ds you will find out that energy is conserved if you do the calculations.

 

[Pythagorean]

There isn't such a thing as an infinite time rate of change of momentum, that is there is no infinite force.There also isn't any such thing as an infinite jerk because force and the time rate of force must be finite.

It's true he's mixing up terminology, but I think what he's really asking about is all the nth derivatives of position as n --> inf.

In other words, we have position, then:

1st derivative: velocity (multiply by m, you have momentum)
2nd derivative: acceleration (multiply m, you have force)
3rd derivative: jerk (multiply by m, you have yank)
4th derivative: ?

Obviously, for you to get from 0 jerk to X jerk, you have to have a change in jerk (otherwise the functions not continuous right?)

I think he's asking why we don't ever consider the higher derivatives.

 

[PJC01]

It's great that you are thinking about these conceptual conundrums! Forces, yanks, and torques are all related to the concept of motion and movement. Let me try to explain them in a more scientific way.

First, let's talk about forces. A force is a push or a pull that can cause a change in an object's motion. In order to move an object, we need to apply a force to it. This force can be applied in different ways, such as pushing, pulling, or even gravity pulling an object towards the ground. Forces are important because they are what allow us to change an object's position and cause it to move.

Now, let's talk about yanks. Yank is a term used in physics to describe the rate of change of force. In other words, yank is how quickly a force is applied to an object. For example, if you push a box with a constant force for 1 second, the yank would be the same as if you pushed the box with the same force for 2 seconds. So, yank is just another way of describing the force applied to an object.

As for torques, they are related to rotational motion. Torque is a force that causes an object to rotate around an axis or pivot point. Think of a door being opened - you apply a force (push or pull) at the edge of the door, but the door rotates around the hinges (the pivot point) due to the torque applied. So, torque is also a type of force, but it causes rotation rather than linear motion.

Now, to answer your question about why force is considered more important than yanks or torques - it all comes down to how we measure and quantify these concepts. Force is a fundamental physical quantity that can be measured and described using Newton's laws of motion. Yank and torque are just different ways of describing force, so they are not considered as fundamental quantities.

Lastly, let's address your concern about torque defying conservation of energy. When an object is rotated, energy is transferred from the force applied to the object to the rotational motion. This does not defy conservation of energy, as the total energy of the system (object + force) remains constant. In the example you mentioned, the force applied at the edge of the object is spread out over a larger distance when the object is rotated, so the amount of force absorbed at the pivot point is not greater than the