Gravity

[Magnum]

All,

You ask, “Where does the force come from.”
We know that CF is the lack of force AKA ghost force. It is the force that makes an object travel in a straight line even when it is traveling in a circle.
Lets place a pendulum in Jims train and say the train is going a constant speed of 60mph. The pendulum, if only aloud to swing from the inside to the outside, would lean to the outside of the train. Vary the speed of the train and the pendulum would begin to swing.
Now the same could be said if the pendulum were only be aloud to swing in the same direction of the train.
Change the track from a flat plane to a up and down track and youÂ’ll see that the pendulum no longer need the train to vary its speed to make them swing. As long as they are swinging in the direction of the train.
The force comes from the weight having to travel in a straight line.

[winkle]

so one ball going faster than the train and the other ball going slower than the train both balls behave in the same fashion ?

i never was in a hay trailer but when i was young spent a goodly amount of time in a cotton picking trailer and it was always easer to walk to the back than the front unless the tractor was backing up

[Fletcher]

where is the energy source

Good question. I've been trying to figure that one out myself. I think is has something to do with time, relativity and speed, but not in the Einstien way. I'll see if I can work out an explaination.

A similar question is why does CF quadruple when you double the object's velocity?

Just some thoughts. N.B. I try to stay away from simply following formula's & try to form mind pictures to rationalize what's happening instead. This explanation works for me though it may not be technically accurate & others may do a better job or dispute its relevance.

Centrifugal Force is not a real force, but its originator that gives rise to the observation of CF, Centripetal Force, is. Centripetal Force is the restraint that hinders an objects direction of travel in a straight line & makes it conform to a new path (curved in this instance).

I have the impression that it is commonly believed that CF is a force that results simply from an objects Inertia. That is, its tendency to stay at rest or in motion in a straight line. This imo is only part of the answer about CF & why it quadruples as velocity doubles. If it were Inertia only then the objects velocity would not alter the CF, so something else is happening to explain it quadrupling.

The Kinetic Energy formula or energy of motion is KE = 1/2mv^2. This could be written as (1/2m) v^2 i.e. half mass (Inertia) times velocity squared.

As an object doubles its velocity, it quadruples the CF it generates. It also quadruples its Energy. Coincidence ? What I mean is that when an object has straight line velocity it has energy proportional to that velocity but it is not linear. Double the velocity, quadruple the energy, same as the CF scenario. It seems they could be related ?!

Momentum (mv) is a vector quantity. The Law of Conservation of Momentum requires the summing of the momentum vectors. The vector representations (mv) are an arbitrary scale & are summed in all directions to give the resultant net vector. The scale chosen is mass times velocity (mv) but it could be any scale. For example, it could use an energy equivalent scale of 1/2v^2. They would all still cancel to a net vector quantity for the system.

If we look at an example of a bullet fired horizontally & impacting with a wall in front of it we know how to calculate the energy of the bullet at moment of impact. We use the KE formula.

If we angle the wall so that it deflects the bullet rather than stopping it we know that the wall must put up an equal resistance to the energy of the bullet to cause it to ricochet. Equal & opposite reactions. This is analogous to the Centripetal Force (CF) in a wheel. The faster the velocity of the mass the more deflective force must be summoned to change the weights path.

In a wheel the rim or whatever easily puts up the force required to deflect the weight. The restraint that keeps the weight orbiting at the same radius is constantly absorbing & deflecting the energy from motion of the mass. So CF can be thought of as a kind of 'pressure' exerted but can only be used when the weight is allowed to move.

In summary, imo CF is a measure of the resistance to a body's Kinetic Energy which is a part function of its mass or Inertia.

Gotta stop now, this is getting too long winded.

[ovyyus]

As an object doubles its velocity, it quadruples the CF [inertia] it generates. It also quadruples its Energy. Coincidence ?

Beautiful.

[jim_mich]

Thank you Fletcher...

The vector representations (mv) are an arbitrary scale & are summed in all directions to give the resultant net vector. The scale chosen is mass times velocity (mv) but it could be any scale. For example, it could use an energy equivalent scale of 1/2v^2. They would all still cancel to a net vector quantity for the system.

This has bothered me why the two used different formulas. You have given me the answer as to why the formulas for CF and KE are different from that of momentum. It seem that since momentum is only a vector quantity it doesn't require the more complex formula, so it 's kept simple.

[Wheeler]

After posting my last little note, I headed for work and felt like I must of got kicked in the butt by the horse that was pulling the hay wagon.

winkle wrote:

never was in a hay trailer but when i was young spent a goodly amount of time in a cotton picking trailer and it was always easer to walk to the back than the front unless the tractor was backing up

Winkle,Bill
I realized that the reason we got to the back of the wagon easier is because we were adding speed (so to speak) to the forward motion of the wagon. It's the Einstein theory of relativity kind of stuff.

When we walk to the back of the wagon, we shorten the time it takes for the wagon to move to us because we travel to the rear while the wagon moves forward.

We are approaching the rear of the wagon, while the wagon is approaching us.

[Mr.Umez]

This one is for Jim_Mich;

The kinetic energy formula is directly related to the momentum formula and represents the amount of work needed to change an object's momentum. It is really quite clever and simple once you see the relationship.

The same idea applies to rotational momentum and rotational energy as stated by Fletcher.

I hope the diagram below explains it.

[jim_mich]

Thanks Mr.Umez,
You show energy is the work required to change an objects momentum. I assume the reverse is true; energy is work produced by changing an objects momentum.

[Wheeler]

Jim

Thanks Mr.Umez,
You show energy is the work required to change an objects momentum. I assume the reverse is true; energy is work produced by changing an objects momentum.

I don't think you can get work, or energy from changing momentum. You need energy to change momentum. The work would be what happens after the momentum change.

[rlortie]

Wheeler,

And all along, I thought that any motion in mass was considered "work"

Accelerating, decelerating or changing paths, as long as it is mass in motion it can be defined as "work", and as such requires a force. Kinetic while accelerating or in a stable motion and inertia when coasting or slowing down.

A weight falling is at work, kineticly energized by gravity and will build induced inertia until it hits the ground. The ground being the equivelant of Centripetal force in a wheel.

If anyone believes this is incorrect, please advise, or ignore if you feel it is just a play on words as I do!

Ralph

[graham]

If you are on this train and walk forward,you will be exerting a force to the floor of the carriage that opposes the motion of the train thereby slowing the train by an amount equal to the applied force.

If you walk towards the rear of the train, you will be slowing down, while the force applied to the to the floor of the carriage to move you back will increase the trains speed by an amout equal to the applied force.

Everything cancels out , just as it does when we try to design a gravity powered wheel

JB where are you ???

Graham

[Mr.Umez]

For Jim_Mich again,

Yes, you are exactly correct. When you change the momentum of an object, energy is either required or given off.

[Fletcher]

It gets even worse in a wheel environment Graham, as you know. Those equal & opposite forces of walking back & forwards thru the train assist or impede the train or the walker proportional to their masses.

In the wheel these equalizing forces become torques around the central axle. If the reactions equalize vis a vis the torques equalize, then every time we apply some conservative force to reposition something inside the wheel, there is no net gain in torque & it zero sums.

Jim_mich is exploring the thought that Inertia itself can provide the platform to leverage off. This still raises the question of where the excess energy will come from to unbalance the experiment & as we have discussed it takes energy to overcome momentum to reposition weights.

Inertia is an 'innate state' of matter but it also is a fundamental building block of Newtonian physics which explains the maxim "for every action there is an equal & opposite reaction" & thus why momentum is conserved which we all know too well.

One way is as Bill advocates. Introducing energy into the closed system via the environment, perhaps as heat. This would seemingly break the conservative force stranglehold that we have all experienced till now.

So if you can never break the partnership of action with reaction then there must be another way to deal with them. JMO's.

[jim_mich]

This still raises the question of where the excess energy will come from to unbalance the experiment & as we have discussed it takes energy to overcome momentum to reposition weights.

Rebalancing the weights is no problem. I had that part solved a long time ago. The weights move and the wheel turns 180 ready to start again. The CG rides a circle from top around to bottom, then spikes back up to the top as the weights swing, ready for the next 180. (Or maybe it won't work?)

The excess energy seems to come from the CF of two weights moving at different speeds. Didn't Bessler say they gain energy from their swinging?

[Wheeler]

Jim wrote:

energy is work produced by changing an objects momentum.

Mr.U wrote

When you change the momentum of an object, energy is either required or given off

.

Wheeler writes
I may misunderstand you two, but I wonder if you could make it clearer for me.
In Jim's quote, I was thinking that work was produced by energy??

Am I totally off on this.

I am not trying to dispute your knowledge, just understand a little better.