Wheel acceleration...

[bluesgtr44]

Hey Jim, thanks for the response. I was looking at an old bookmarked website.... http://www.glenbrook.k12.il.us/gbssci/p ... u6l1e.html ....and it got me to thinking about CpF's inward/outward force and the point of application of the force.

On another thread, someone mentioned the old physics example of swinging a ball on a string. The string is the containment for the force in this example....so, we go to the amusement park and the old "spindle top" ride where one can get nailed against the wall as CF builds up and it is the wall that is the containment for this force...am I wrong on this?

Basically, I was thinking the ball (weight) on the string is actually a pulling force and the person (weight) in old "spindle top" is a pushing force, they just have different points of application. Since you had a design in mind using CF, I just thought I'd ask as to how you might be applying this aspect of it.....


Steve

[bluesgtr44]

Here is another tidbit from that site....I think it is a good example of the push/pull application that can come about from this. And then again....I could be wrong....


Steve

[rlortie]

Steve,

Excuse my ignorance here (or is it)...

I have a problem referring to both CF and CpF both in a push-pull frame of mind. CF is the outward force and CpF is the wall that retains you from being flung out in a straight line.

IMO CpF is better explained as that which retains a given radius of a mass. CF is an inertial property that wants to keep the mass traveling in a straight line. Inertia is not in any of my reference material ever referred to as a "force", it is a resistance to motion action or change.

Cpf is the "component" of force (the wall) acting on a body in curvilinear motion that is directed toward the center of curvature or axis of rotation.

CF is the "Component apparent force" on a body in curvilinear motion, as observed from that body, That is directed away from the center of curvature or axis of rotation


Both being either apparent or a component of force is referenced as either to or from the axis of rotation. To maintain a true circular path both must negate each other. I have yet to conceive how this can by utilized to promote radial motion in a wheel. I can pull or push on the axis of a wheel all day long and all I end up with is a bent axle.

Ralph

[rlortie]

Steve,

your water accelerator in my opinion is a very poor example to be used here.

The cork is less dense than the water. Therefore requires less CpF than the water by displacement or mass. See "Centrifuge"

Ralph

[bluesgtr44]

Hey Ralph....

I have a problem referring to both CF and CpF both in a push-pull frame of mind. CF is the outward force and CpF is the wall that retains you from being flung out in a straight line.

I might not be using the terminology correctly....but, going by what you say above...CF is outward, if connected to a string and swung around...wouldn't the force be pulling on the string? But, if we did away with the string and put the weight in a wheel....wouldn't the force be pushing against the rim? The difference would be the point of constraint, I guess is what I am looking at....the wheel frame, of course would be connected to the axis and is acting as the string.....so to speak. The weight, though...acts differently is these two scenarios. With the string it is always going to be pulling....with the rim, it has to reach a certain speed before it can apply that force accordingly.

your water accelerator in my opinion is a very poor example to be used here.

The cork is less dense than the water. Therefore requires less CpF than the water by displacement or mass. See "Centrifuge"

You're probably right, Ralph...not the best example. The part of this that I thought would translate is the displacement....the water being forced outward, pushing against a rim is actually leveraging the corks inward. Now, take away the rim and attach a string from the jar of water, around the axle using a pulley and then come around and attach to the cork. Would not the jar of water, in this scenario....be pulling the cork inward?

I might be grasping here, but "put the cart before the horse..." and also the section where he discusses the FORM of objects...when I was just browsing my bookmarks....looking for anything that might jog something...I got to thinking about a point of application if one was to actually be able to use this force in a mechanical way to shift the weights.


Steve

[jim_mich]

Like I said, "when the weight is placed in the middle of the lever then does it push or does it pull?" This is why I just use CF to indicate type of force and not direction. One CF is always outward and one CF is always inward and the two are alway equal and depending on which side the constraint is at determines if we call the force pushing or pulling. Maybe I should use CForce or CCF to indicate this force? I think it's silly to have two names for the same force depending on which direction we are viewing it from.

[rlortie]

Steve,

I will break your above statements down for clarity. Keep in mind that for obvious reasons this is "my opinion"

I might not be using the terminology correctly....but, going by what you say above...CF is outward, if connected to a string and swung around...wouldn't the force be pulling on the string?

The apparent force is pulling on the string but the force itself is created by inertia. The resistance to action or change. The mass wishes to follow a straight path, the applied force on the string is CpF that over comes the inertial properties, thus retaining an orbital path.

But, if we did away with the string and put the weight in a wheel....wouldn't the force be pushing against the rim? The difference would be the point of constraint, I guess is what I am looking at.

Again I reiterate that this is my opinion! No! I do not believe the force would be pushing against the rim. The force in reality is inertia still attempting to keep the mass in a straight trajectory, with that in mind it is pulling against the rim.

the wheel frame, of course would be connected to the axis and is acting as the string.....so to speak. The weight, though...acts differently is these two scenarios. With the string it is always going to be pulling....with the rim, it has to reach a certain speed before it can apply that force accordingly.

I do not think the weight acts differently only the manner of containment, nor is there actually two scenarios. In either case inertia is creating the force and the manner of containment whether by string or physical barrier (rim) will facilitate the same end result.

the water being forced outward, pushing against a rim is actually leveraging the corks inward. Now, take away the rim and attach a string from the jar of water, around the axle using a pulley and then come around and attach to the cork. Would not the jar of water, in this scenario....be pulling the cork inward?

In a manner of speaking yes! simply delete the term "pushing against the rim". The larger having greater inertial mass will pull the lesser in. In doing so the gradient between the two become exponential. That is, as the radius of the lesser decreases so does the velocity which reduces the kinetic energy when retained at a given RPM. Once again I refer to the basics and benefits of a centrifuge.

I might be grasping here, but "put the cart before the horse..." and also the section where he discusses the FORM of objects...when I was just browsing my bookmarks....looking for anything that might jog something...I got to thinking about a point of application if one was to actually be able to use this force in a mechanical way to shift the weights.

Obviously it would be a great way to shift a larger weight out while that of a smaller mass is located closer to the axis. The "Put the cart before the horse"statement has also crossed my mind. Form of mass could relate to objects that have an "out of balance" related to their reference point or connectedness. This could be useful when considering CF as a main component in a wheel design.

Biggest problem in discussing this path is that one still has not derived a driving force to create the inertial effect to achieve these results. The idea of using CF or Cpf to drive a wheel completely evades my grasp.

Centrifugal force creates simulated gravity.

EDIT changed radius to axis.

Ralph

[bluesgtr44]

Thanks Jim and Ralph.....this is what started this all for me....

When the subject of circular motion is discussed, it is not uncommon to hear mention of the word centrifugal. Centrifugal, not to be confused with centripetal, means away from the center or outward. The use of or at least the familiarity with this word centrifugal, combined with the common sensation of an outward lean when experiencing circular motion, often creates or reinforces a common student misconception. The common misconception, believed by many physics students, is the notion that objects in circular motion are experiencing an outward force. "After all," a well-meaning student may think, "I can recall vividly the sensation of being thrown outward away from the center of the circle on that roller coaster ride. Therefore, circular motion must be characterized by an outward force." This misconception is often fervently adhered to despite the clear presentation by a textbook or teacher of an inward force requirement. As discussed previously in Lesson 1, the motion of an object in a circle requires that there be an inward net force - the centripetal force requirement. There is an inward-directed acceleration which demands an inward force. Without this inward force, an object would maintain a straight-line motion tangent to the perimeter of the circle. Without this inward or centripetal force, circular motion would be impossible.

So why then is this student misconception of an outward or centrifugal force so prevalent and so stubbornly adhered to? Perhaps like all misconceptions, the notion of a centrifugal force as lodged in a person's head has a particularly lengthy history. Part of that history is certainly attributable to the experience of a circular motion - either as a passenger or driver in an automobile or perhaps on an amusement park ride. Even learned physics types would admit that circular motion leaves the moving person with the sensation of being thrown outward from the center of the circle.

It does state pretty much what you explained, Jim. No need to change around your meaning....;-). I guess I was just looking at the possibility as to whether or not there would be a difference in applying the force pushing on the rim to activate a mechanical action with a pivot point there as opposed to pulling on a chain, line, rope through or around the axle using that as the pivot point.

Hey Ralph....

Again I reiterate that this is my opinion! No! I do not believe the force would be pushing against the rim. The force in reality is inertia still attempting to keep the mass in a straight trajectory, with that in mind it is pulling against the rim.

I don't get this....pulling against the rim? I see it as wanting to push out of the rim to go in a straight line. Now, the shell of the wheel is connected to the axle and I can see that relation....is this what you mean?

I do not think the weight acts differently only the manner of containment, nor is there actually two scenarios. In either case inertia is creating the force and the manner of containment whether by string or physical barrier (rim) will facilitate the same end result.

I think that is pretty much what Jim implied...no matter where I put the pivot, it's going to balance out....

Biggest problem in discussing this path is that one still has not derived a driving force to create the inertial effect to achieve these results. The idea of using CF or Cpf to drive a wheel completely evades my grasp.

It does me also, Ralph....but what a force it is! I can see why Jim sees that potential and wants to try and tap into it.....it's brutal in most of our persuits, so if we can't beat it....use it! And, no......I have not been very successful in this endeavor any more than any of my others.....but, I'm workin' on it!


Steve