The Lee-Tseung Lead Out Theory

[ltseung888]

I shall assume that all forum members could understand Slide 10.  That Slide is correct in both Physics and Mathematics.  Now I shall re-discuss Slide 11.

Translation of presentation slide 11.

Tseung: "Let us apply the Law of Parallelogram of Forces to analyze this system.  Most of you have studied this Law in Physics in Secondary School.  Let us assume that the bob has been displaced and remains in the new displaced position.  In this case, there are three forces at equilibrium.  These three forces are: the horizontal force F which is still 10 units; the weight of the bob which is still 60 units and the tension of the string T1.  T1 can be calculated via the vector arithmetic or the parallelogram of forces.  It is equal to the diagonal of the parallelogram formed by the two vectors Mg and T.?

Tseung: ?At equilibrium, the angle of the string is ?a?.  Tan(a) = F/Mg = 10/60.  Thus in this case, the angle ?a? is 9.46 degrees.  This is strictly mathematics and cannot be wrong.  T1 can then be accurately calculated to be 60.84 units.?

The spreadsheet file is available for anyone who wants to do the checking.

This is effectively the first Lee-Tseung pull.  Note that we are discussing forces only.  The First Lee-Tseung pull assumes that the pull is 10 units of force horizontally.  The three forces (Weight, Pull and Tension of string) are at equilibrium.  The relationship can be expressed mathematically via vector arithmetic or the Law of Parallelogram of Forces.

This mathematics cannot be wrong.  The Physics of three forces at equilibrium obeying the Law of Parallelogram of Force also cannot be wrong.

Now please comment on this Slide 11.  Can any one find anything wrong with this Slide 11?

[Top Gun]

For those who do not understand vector addition or parallelogram of forces, please read:

http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0016624.html

In physics and applied mathematics, a method of calculating the resultant (combined effect) of two different forces acting together on an object. Because a force has both magnitude and direction it is a vector quantity and can be represented by a straight line. A second force acting at the same point in a different direction can be represented by another line drawn at an angle to the first. By completing the parallelogram (of which the two lines are sides) a diagonal may be drawn from the original angle to the opposite corner to represent the resultant force vector.

[shruggedatlas]

Now please comment on this Slide 11.  Can any one find anything wrong with this Slide 11?

Need more info for clarification, please.

1.  The horizontal force is a persistent force, correct?
2.  What is shown is a static scenario at equilibrium, correct?  (This means the bob can go no higher to the right, given the horizontal force of only 10 units.)

If the above assumptions are correct, I think it would be easy to test it using nothing more expensive than two hook scales.  You hang one scale and attach a string with a weight on it.  Let's use your units of 60, so let's say a weight of 6 kg (60kg would be too heavy for us to play with).  Then, take the second hook scale, and use it to pull horizontally on the weight until that scale reads 1 kg.  Then, freeze your position and measure the angle of the weight.  It should be near 9.46 degrees, correct?  Also note the reading on the top scale, which should be near 6.084 kg, correct?

What do you think?

[Top Gun]

Now please comment on this Slide 11.  Can any one find anything wrong with this Slide 11?

Need more info for clarification, please.

1.  The horizontal force is a persistent force, correct?
2.  What is shown is a static scenario at equilibrium, correct?  (This means the bob can go no higher to the right, given the horizontal force of only 10 units.)

If the above assumptions are correct, I think it would be easy to test it using nothing more expensive than two hook scales.  You hang one scale and attach a string with a weight on it.  Let's use your units of 60, so let's say a weight of 6 kg (60kg would be too heavy for us to play with).  Then, take the second hook scale, and use it to pull horizontally on the weight until that scale reads 1 kg.  Then, freeze your position and measure the angle of the weight.  It should be near 9.46 degrees, correct?  Also note the reading on the top scale, which should be near 6.084 kg, correct?

What do you think?

Dear shruggedatlas,

Brilliant.  In the first Lee-Tseung Pull,

(1)   The horizontal force is indeed persistent.  In other words, the pendulum bob is pulled and displaced.  The pendulum bob has not been let go yet.

(2)   The analysis is indeed at the highest point with no motion.  This is like your pulling the swing with a child sitting on it.  You first pull the swing at an angle before letting go.

The experiment you described is a standard secondary school Physics Experiment.  It has been verified a few million times Worldwide over the centuries - since the days of Newton.

It cannot be wrong.  I am interested to see if chrisC, Keon1, Tinu or others can possibly find something wrong.  Tinu used his objection of the previous mistake of using the incorrect unit for force to dismiss the whole thing.  I am interested to see his comments without that mistake.

Thus Slide 11 cannot be wrong.  It is standard secondary school physics material.

[ltseung888]

Dear Top Gun,

Thank you for your helping out.  Your questions really helped me to focus on specific issues.

I am confident that nobody can possibly find fault with Slide 11 now.  There is no hurry.  I shall give plenty of time (a few days) for people to comment.