The Lee-Tseung Lead Out Theory

[Kul_ash]

3. As far as Mr. Tseung wrote in his earlier post that the first pull is constant. Now you tell me to go to park and try to push or pull child on swing in horizontal direction. My dear friend, tell me one thing, if I am going to apply a constant initial force, my hand are going to move radialy along the arc length of Pendulum. Will that be a constant horizontal force? I am applying initial pull because I want to raise the swing to a certain height to give it a momentum! "I AM DOING THAT WORK". According to your theory, I will be just moving it horizontally and "lead out" gravity will give it upward movement. Tell me how in the world is that possible? Have you yourself ever taken a child to a swing?  And now if you are talking just about the horizontal push, then it is same as the pulse force which is not constant force. Please make up your mind.

Dear Kul_ash,

Let us focus on Physics and Mathematics.  Do not add insults in your otherwise logical and high quality posts.

The first Lee-Tseung Pull analysis compares the Force, Displacement, Work and energy in the two positions.  Position A is the initial rest position.  That is Slide 2.  There are two forces Mg and T.  They are equal and opposite.  There is no displacement and no work and hence no energy.  This is used as a reference point.

Position B is the maximum RHS displaced position.  There are three forces: Mg, T1 and F.  These three forces are at equilibrium.  There is vertical and horizontal displacement.  Thus there is work done compared with Position A.  Work done implies energy supplied to the pendulum system.

All Mr. Tseung did was to apply O-level physics to the two positions.  Every equation and every step is produced in this improved presentation.

The park example is to show that any Pull or Push at any angle may be able to move the pendulum from the rest position.  However, those are not ideal Lee-Tseung Pulls.  They are not efficient or even negate the Leading Out of gravitational energy if applied at the wrong time.

Please discuss Slide 3 again.  Now you understand that Slide 2 and 3 (Plus 4,5 and 6) are used to compare the force, displacement, work and energy at two different positions.  Can you possibly find anything wrong with the mathematics and physics?

Dear Top Gun,
First of all I did not mean to insult you or any one. I am sorry if I have done that. I am here for acedemic discussion and I will refrain myself from personal attacks from now on.

Well, that being said, I will come back to your querry of "What''s wrong with the analysis?" . Well there are so many things wrong.

1. Your Slide no.2 indicated T and mg are equal and opposite and will cancel each other at any point of time. Am I wrong?
2. From your slide no. 3 onwards, you suddenly discard that and start treating T and mg in equal direction supporting each other. How is that possible? You totally forget that T and mg cancel each other at any position and that is why Pendulum system is in balance. Refer your own slide no. 2.
3. You consider F shown as additional horizontal force. To lift pendulum from initial position to lifted position, you "HAVE" to give tangential force. It is not possible to get only horizontal movement with your constant force.
4. You yourself in slide no. 2 show T = mg. Then Slide three you show two forces only i.e F and mg and show "INCREASED" T1 from T. Now if mg is constant and there is no vertical component of your purely horizontal force F, then what force increased T to T1? "lead out" gravity? Then why it is not shown in fig?
5. Again in this slide you just show two forces F and mg and resultant force of F and mg acting downwards. What happened to a force T? Why it is not in the system? And if T1 is downwards and its creating vertical movement, then that movement has to downwards to? Then how come you suddenly again changing direction of vertical movement and its going upwards? If movement is upwards then how come T1 is responsible for it?
6. In your force calcultations, to calculate vertical work done, you have used formula T1 x L(1- cos a)
  And value of your T1, you have used is mg. Well what happened to increased T1 value? How did it get back to mg? If T1 = mg, then what is the meaning of your slide no. 3? In that case T1 = mg and mg = T, then T = T1 and that means no increase Tension in string. Isn't that contradict to your comment saying, the moment you apply force to system, tension in string is increased? Then where is that increased value?
7. So in all you have overlooked so many things. Firstly, ignoring T totally. Ignoring direction of forces. Ignoring directions of work done, ignoring added forces, adding unknown forces etc.
8. There is no 0 level physics involved in this my friend. I am sorry to say this, but again your assumptions themselves are totally wrong unless and untill your write new physics.
9. For your better understanding, I have drawn this basic fig. explaining forces on system and what force is doing what work. Please study it and compare it with your own theory:

[Top Gun]

Dear Kul_ash,

Let us enjoy this juicy technical debate.

1.   Your Slide no.2 indicated T and Mg are equal and opposite and will cancel each other at any point of time. Am I wrong?

Slide 2 shows the initial rest position.  There are only 2 Forces: Mg and T.  Mg will remain the same in this discussion as it is the weight.  T is the tension of the String which is expected to change.  They are equal and opposite only in the initial rest position.  As soon as other forces are added, they will no longer be equal.

2.   From your slide no. 3 onwards, you suddenly discard that and start treating T and mg in equal direction supporting each other. How is that possible? You totally forget that T and mg cancel each other at any position and that is why Pendulum system is in balance.  Refer your own slide no. 2.

Slide 3, 4, 5, 6 refer to the second position after a horizontal Force F has been applied to pull the pendulum bob to the maximum RHS position.  The tension in the string T has changed to T1.  That is why T never appears in slides 3, 4, 5 and 6.  To be more exact, T1cos(a) is now equal to Mg. We are saying that after F has been applied to the system, the tension of the string will increase to T1.  The vertical component of T1 (T1cos(a)) = Mg.  The horizontal component of T1 (T1sin(a))= F.

In your diagram, box 2, you stated: ?To lift bob from A to B, we have to give Constant Tangential force F.  This is where your misunderstand of the Lee-Tseung theory begins.  If you have done the parallelogram force experiments in O-Level Physics (O-Level is the term used in England.  You may have a different term in your country.  In USA, I believe the term used is High School.), we can indeed use a final horizontal force F to pull the pendulum bob from position A to B.

Please confirm your understanding up to this point.  (Other parts to follow).
The two confirmations I am looking for are:
(1)   The tension of the string is increased from T to T1 after a horizontal force has been applied.
(2)   We can use a ?final? horizontal force F to pull the pendulum from position A to B.  There is no need for a constant tangential force. 

[Kul_ash]

Dear Kul_ash,

Let us enjoy this juicy technical debate.

1.   Your Slide no.2 indicated T and Mg are equal and opposite and will cancel each other at any point of time. Am I wrong?

Slide 2 shows the initial rest position.  There are only 2 Forces: Mg and T.  Mg will remain the same in this discussion as it is the weight.  T is the tension of the String which is expected to change.  They are equal and opposite only in the initial rest position.  As soon as other forces are added, they will no longer be equal.

There you go my dear friend! You said it! It is the added force that is responsible for added tension in string. According to your theory, added force is only going to give horizontal displacement  And vertical force is coming from "lead out" energy! Where did it come from? Did you add it and if gravity did it then how? And then why did you required initial push for gravity to give you energy? What is the meaning of your statement "as soon as other forces are added, they will no longer be equal"?
If added force is only going to do horizontal work, what component of the system is adding tension in string?
And the most basic question: Have you seen it practically working ever?

[Kul_ash]

For your simple understanding:

If you have a pendulum that has a wheel at top and and is allowed to move horizontally only, then applied force F will do the X m displacement in horizontal direction.
Now if you have a regular pendulum, the applied force will create horizontal displacement < X m because some part of applied force will go in giving vertical displacement.

According to you theory, I should get X m horizontal displacement in both the cases and still get vertical displacement in second pendulum because gravity is adding energy to the system!

I challange to prove it by experiment!

[Kul_ash]

Please confirm your understanding up to this point.  (Other parts to follow).
The two confirmations I am looking for are:
(1)   The tension of the string is increased from T to T1 after a horizontal force has been applied.
(2)   We can use a ?final? horizontal force F to pull the pendulum from position A to B.  There is no need for a constant tangential force. 

I am confused again and again!! What is a "final" force? Is it constant or is it one time? Please clarify it! Does 0-Level physics say that you can apply a constant horizontal force to pendulum?