...you can watch at : http://www.youtube.com/watch?v=NFJPQLhWPvA with the title "Falling Meter Stick With Coins".
In a classical lab-demo (Hinged stick-falling ball),you can see the acceleration paradox,when a ball and a board are released together,the end of the board outstrips its center of mass,leaving the board behind.
That is,if you allow a board to rotate under the influence of gravity,the free end will accelerate at a rate greater than "g".
We know that,gravity accelerates all objects at same rate...on the vertical line.
This time,the relation between angular acceleration and linear acceleration,gives us a free-fall paradox (you remind the theory about the closed loop in gravity and the null result...).
Here can be an "open gate" for our topic :if between two points,on the vertical line,for the same mass,we can obtain two different falls (velocity,acceleration,momentum....)...their inequality,can be a starting point for us...a "heavy angular fall" vs. an "easy linear up".
All the Bests! / Alex
Hi Alex,
I think it happens because the ruler is rigid and fixed at one end. The middle of the ruler wants to fall at freefall speed. But because one end is restrained it cant fall at freefall speed. The difference is transmitted as torque to the free moving end through rigid lever action and so the end falls faster than freefall speed. Conversely the end that is now falling faster than freefall will be exerting a negative torque, trying to slow the whole thing down. Only one point on the ruler falls at freefall speed, every other point being either faster if further away from the fulcrum or slower if closer. The whole system finds force equilibrum, by redistributing the kinetic energy.
In my mind it´s not a paradox, sadly I think if one analysed the movement and applied integral calculus then it would be net neutral so the whole system kinetic energy would be the same as if the ruler were dropped half the height with both ends free, of course I could be wrong. The simplest way to test would be with impact analysis using a really rigid beam with a bit of weight to it:
Test1:
allow a 1m beam to swing downward, one end travelling 40cm. The other end travelling 0cm. Analyse the impact force by seeing how far a pencil can be pushed into a slab of plastiscine by the fast moving beam end.
Test2
allow a 1m beam to drop freely, neither end restrained, through 20cm. Analyse the impact force by seeing how far a pencil can be pushed into a slab of plastiscine by the middle of the beam.
I think in both tests the resulting impact will be the same when many drops are performed to eliminate noise.
Hi Yucca !
The term "paradox" is not mine...you can encounter on net.
Paradox is a statement that seems absurd or self-contradictory,but may be true.
You can watch short movies on net with the tag "Falling chimney",regarding the same puzzle.
If you type "Falling stick" on net,you can find a plenty of information:it's simply classic lab-demo in elementary physics.We need proof no more ...the phenomenon is real...nothing new under the Sun!
All the Bests! / Alex
Hi Alex,
It doesn't seem absurd or contradictory to me, just normal rigid body dynamics in action. But maybe it's a paradox to some?
best, Yucca.
My explanation above is somehwat abstract, it's difficult to explain it simply. But imagine this thought experiment, it will make things alot clearer:
Take a 1m long very rigid and lightweight stick, say a thin carbon fibre pole.
Pivot one end of the stick on the edge of a table.
Now 25cm from the pivot point attach a length of string, tied to the stick.
On the free end of the string hang a 1kg weight.
Now lift the sticks free end until it is horizontal, the 1kg weight hanging on the string below.
Now release the stick....
The 1kg weight will fall at nearly 1g, but of course we all know the end of the pole, 1m away from the pivot, will be accelerating vertically alot faster than 1g because it has to cover more distance. The end is being forced down by the inboard weight, acting through the rigid body of the stick, forcing the sticks tip to accelerate well beyond 1g.
This is exactly the same as a uniform ruler doing the same thing, only in my thought experiment above the effect is exaggerated for easier visualisation.
The whole system acts perfectly conservatively, no magic here unfortunately.
Hi Yucca !
In my opinion,the root of this paradox (apparently contradiction that,maybe contains within it a germ of truth ) is reffering to that fictitious "point" mass.
The gravity applies to every atomic nucleus,but the mass has a different distribution :linear (a board) or compact,around a center (ball).
So,the real distribution of mass (atomic system),can "unlock" this real (or illusory...?!) puzzle.
Anyway,the classic physics teaches and demonstrates (see lab-demo) that ,here is a net difference if a mass falls on a vertical line (without inertia ),or on a circular,curved line/trajectory (with inertia)...
The next step is on-the -spot:to imagine a closed loop =curved fall down+linear rise up.
At: www.geocities.com/iacob_alex/Some_Drafts/untitled023.jpg on the top of the page ,you can see this trajectory(blue line),for a certain application.
All the Bests! / Alex
Hi Alex,
I'm still unsure, do you believe this effect might have hidden OU aspects to it?
I suppose the concept of "point mass" could be considered fictitious. But even if plancks constant does not apply to matter, if matter has infinite resolultion, if it is not a discreet system, then it will act exactly the same.
I fail (and it may be my failing) to see how whether it's a discreet or continuous system comes into play in this effect. Could you explain that a little further for me please?
Do you agree with my thought experiment above using the carbon fibre stick and weight? If so, can you see how a uniform stick obeys the same effect, just not as exagerated.
I assume you're not making the mistake of thinking all of the falling mass is at the tip, so I'm curious to know if you think there's something I may have missed here.
Quote from: iacob alex on June 08, 2009, 03:49:28 PM
Anyway,the classic physics teaches and demonstrates (see lab-demo) that ,here is a net difference if a mass falls on a vertical line (without inertia ),or on a circular,curved line/trajectory (with inertia)...
The next step is on-the -spot:to imagine a closed loop =curved fall down+linear rise up.
At: www.geocities.com/iacob_alex/Some_Drafts/untitled023.jpg on the top of the page ,you can see this trajectory(blue line),for a certain application.
All the Bests! / Alex
Curved fall down, linear rise up. I think the potential and kinetic energies involved in both will sum to exactly the same amount, just the interplay between potential and kinetic will be distributed differently in each case.
If you have a hunch that there's something to it then I can only recommend experimenting. In this field the experiments can be made with real cheap materials and really easily.
I'm not saying there's nothing to the idea, just that it doesn't excite me enough to go to the top of the list of experiments to perform. Weird effects can often be found while looking for other things, experimenting is good!
Something that's somewhat related is Bruce De Palmas experiments with a falling object. He dropped it spinning and he dropped it not spinning. He got different acceleration profiles....?:
http://depalma.pair.com/gyrodrop.html
Cheers, Yucca.
Thank you Alex for posting.
What I see is that all the weights on the yardstick want to go down at the same time. But the yardstick is in the way. So there is more pressure on the yardstick to go faster on the loose end because of the weight of the upper end on the table. So it is accelerating the loose end of the yard stick.
....can give access to a simple unbalance relation ,for a possible mass circulation (in a closed gravity trajectory) : curvilinear fall down acceleration> linear jump up acceleration...?!
All the Bests! / Alex
...can be expressd with an elementary problem (test) : a rotating stick.
Some expressive comments you can find at: www.astrophysik.uni-kiel.de/~hhaertel/PUB/mathe_phys.pdf
" Mathematics cannot express and answer to the question about the causality behind this process.There must be "something" besides gravity".
A test (and calculus...) can be made for angles larger than 40 degrees (cos2/3).
The essence of mathematics is to measure,but of physics is to explain "what?"...
All the Bests! / Alex
...or "falling stick/chimney..." has a direct and essential connection with any spoke(let's say stick...) that falls and uses the power of gravity.
Any design must have at least one spoke("stick") and a rim,or two spokes (in a lever/pendulum concept) or more,as you like...
As you see,the "g" paradox problem, is inevitable ("is in the cards"),if we want to play reality,but not a vain product of the imagination.
All the Best! / Alex
...you can watch and understand ,in a more accurate manner,if you make a single click :
www.youtube.com/watch?v=Mi16ws35JIQ
All the Best! / Alex
Quote from: iacob alex on July 03, 2009, 03:31:07 PM
...you can watch and understand ,in a more accurate manner,if you make a single click :
www.youtube.com/watch?v=Mi16ws35JIQ
All the Best! / Alex
Very nice Gravity demo, Thanks!
Jerry :)
Hi Jim!
I agree with you...but we have one more problem,if you watch the last message at "Self moving hoop"( www.youtube.com/watch?v=GuTMYgQDUzs ).
So,now we have two problems:
-falling stick with pennies
-Milkovic's pendulum
Anyway,in any attempt to imagine some designs,I think we must take into account the both situations.
You know,the best teacher is reality...
All the Best! / Alex
Hi Jim!
It's a good idea to take a concentrating look at Milkovic's site.
I had an e-mail connection with him,some years ago and everytime he has some news,I receive an announcement.
You can discover that the gravity fall is so complex,thinking of a falling stick,chimney,pendulum,solid state,elastic bodies ....
Regarding Maschinen Tractate ( your MT 25 first choice...),I will open a new topic.
All the Best! / Alex
Hi Jim !
I visited the 1-143 drawings from Maschinen Tractate .
About your comment regarding MT25,first question is :really can work the mass-driver?Had you made an easy experiment(not on the paper,or on the screen..) ?
Usually,the people imagine an obsessive "wheel",some asymmetric "arabesque" rough outlines,representations that you can see on persian carpets or on the oriental temple walls...this is statics.
If you reduce these attempts to the minimum lines (left side-fulcrum-right side),you discover a simple ...weighting equivalent "machine" ,with a tiny swinging motion about the horizontal line,nothing more.
Gravity dynamics is something different,this implies a certain fall,firstly : an Atwood machine with a heavy pulley,can tell you more...
In my opinion,gravity dynamics is something different,in the Archimedes line.
Sorry,but this forum has no experimental builders
All the Best! / Alex
Hi Jim !
It seems that,you are fascinated about MT 25...so I wish you success.You know that actions speak louder than words.The model is not so difficult,so if you lay your bike on ground,you can use a "free" wheel, as a support for the arrangement of MT25.
All the Best! / Alex
Hi Jim !
Falling stick,falling chimney and others ,all are "Whipp effects".
You can read a lot of things about this phenomena,on net,if you type the appropiate words.
More interesting is the use of this effect , in the animal world.
All the Best! / Alex
Hi Jim !
As usually,somebody proposes a topic ("g" paradox...),and the people moves it elsewhere...
Regarding Bessler's MT25,we have no good news:it doesn't work,you know.
If you have a proposal about it, a certain change on the line of the same design,try to make it in an elementary manner,so to express your thought.
Better is to test it...
All the Best! / Alex
great topic. i love puzzles that make you use your mind..
first we must remember that gravity is an accellerating force, not a constant velocity.
there is a slight time delay between the time the stick begins to move, and the moment of inertia of the (non attached) objects resting on top of said stick is overcome. Thus the stick has a head start before the experiment begins. add in leverage / inbalanced center of mass, and the result is what we see in the experiments. notice that at the approximate center of mass, both stick and object are moving at almost the same rate, and towards the fixed end of the stick, the objects never leave the stick at all.
With milkovic's pendulum drive - this is a completely different thing all-together. The free rolling ball converts most of its energy into kenetic impact against the motionless cart.
When the ball is attached to the pendulum: momentum is conserved, except for the moment when the force on the ball changes direction. during this moment, the force is straight ahead pushing the cart forward. Momentum is still conserved.
This is exactly how his 'water-pump' functions.
no doubt that a pendulum is one of the most efficient devices for converting potential to kenetic energy and back again.
take for example a BOX on a RAMP...
compare this now to a ROLLER SKATE on the SAME RAMP..
you will see that the roller skate is much more efficient at rolling down the ramp. this is no different.
What these two 'problems' have in common, is that people often fail to look at all the factors involved. and even at times intentionally leave out factors that their audience deserves to know about.
While these things may seem strange when presented behind a fogcover, they are certainly not a 'paradox' by any definition of the word.
...as I see the things,is more related to MT18,than to MT25.
"g " paradox (as the people gives the name on net) is interesting because introduces the "whip" effect:an elastic falling stick,as a new lab-demo...
On net,you can find something alike with the label "falling chain".
For PM,this phenomenon is useful to take into account for some designs...
All the Best! / Alex
.....can be seen as a possible paradox (something that seems absurd,but may be true) ,or as a real effect of mass distribution ,when the free falling object is attached to a hinge.
Let's see again the stick (continuous,rigid mass) and the coins ( disperse,bending mass),in a hinged free fall at : http://www.youtube.com/watch?v=NFJPQLhWPvA
If the stick and the coins have the same mass,and repeating the test,we get the same result/effect ,we have an interesting case,maybe useful for the topic of this forum.
Anyway,all experiments of PM (on paper or in reality ),have as a "leitmotiv" ,the left-right replacement,change of distribution of the same mass...
All the best! / Alex
.....can be a simple and apparently lab-demo "trick" (unequally masses and differently starting point/height).
But it can be also,a convincing,simple fact of reality,if we repeat the Galileo's easy experiment,this time with two equally,identically masses that fall from the same elevation,starting in the same moment:
-mass A falls vertically,on a straight line.
-mass B falls on a different trajectory...let's say as a free falling inverted pendulum.
If there is a time (velocity,momentum...) difference,we have an "entrance" to think about the next step(s)...
All the best! / Alex
HI Alex: very nice demonstration, I also read your thoughts about the long arm short arm pendulum, and i must say I think you are right on the money. If a gravity wheel is to work, the weights must not move a great deal... long arm of a horizontal pendulum falling from around 2:45 position and swinging over to the 9:00 O clock position, it is there when CF has released some of its grip that the shift must occurr.
Hi Dr !
If you take a look on net,regarding /"g" paradox/Falling chimney/Falling stick/...so diverse denominations ,about the same simple "unknown" fact...you can discover that,we need to carry simple tests,nothing more.
Some steps you can find at "Gravity wheel of Mikhail Dmitriyev" topic (see May 18-19 ,comments).
Again,Mikhail has no solution,but interesting simple short experiments about pendular fall (pendulum,counterweighted pendulum:fixed arm and variable arm ).
In my opinion,the real answer for the old PM problem,is "around" these easy,simple experiments...
...not a "small " wheel,but a "fit size " of a first degree lever(fixed arm+variable arm).
All the best! / Alex
Good Morning Alex: Your last two sentences, I agree completely, the solution to a gravity wheel will not be found on a small size wheel. A weight falling near the rim of the wheel will take longer to fall than a weight in free fall straight down! I believe this is why Besslers first wheel was 6.5 ft, in diameter, and every wheel thereafter was even larger. Also you notice he slowed them d
o wn? First wheel 60+ second wheel 50 third and fourth 26 under no load. Why? Perhaps to give the weight more time to shift!
Hi Dr !
We can understand so easy the importance of the size ...if we experience a vertical jump down (1meter...2m...3m.....5m....).
We can notice a similar case,with an unbalanced big size lever,free to topple down :here we have an initial torque differece,increasing alike an "avalanche process".
Simply,it's an elementary "butterfly effect":a small difference (initial condition) of a dynamic system,may produce a large variation (final condition),in a long time behaviour.
To replay this "game",we need to feedback this small difference.
No free fall,no "free" power...
All the best! / Alex
Hi Alex: When you say " no free fall, no free energy" what exactly do you mean? How do you propose to capture the energy of a free falling weight and recycle it? I know from my own experiments of smashing lead balls there is great power in a free falling object, but how to use it without destroying your wheel, is the 24,000$ question?
Hi Dr !
Regarding "how to capture the energy of a free falling weight",we can use a pair of weights,attached to a first class lever: this arrangement works as an unbalanced torque,free to develop alike a mass in a free gravity fall.
This motion can be stored as rotational inertia.
Some explicit comments,you can find at this forum,in some topics:
-Heavy hub pendulum
-Torque avalanche
-H/h "puzzle"...
-Long charge=short discharge
-Same input-greater output
-...and others...
Regarding "to recycle" (to close the "loop")...there are some solutions.
Maybe,in the future,I will rent a site on net,and open again my "gallery" of drawings,so to be more explicit.
In this point of time,I am interested to make more easily manifest the concept,or general idea of PM,this "dream machine" :simplicity is the best expression.
All the best ! / Alex
Quote from: iacob alex on June 08, 2009, 12:02:02 AM
...
That is,if you allow a board to rotate under the influence of gravity,the free end will accelerate at a rate greater than "g".
...
Where is the "paradox" ?!
It is not "free fall" (one of the end of the bar is prevented from falling).
Hi !
If you type on Google : "freefall paradox" ...you can find plenty of information ,regarding this subject.
It's a simple fact of reality...
Maybe,this fact in itself is nothing...but it is valuable only for the idea of this forum, attached to it (the search of PM) ...
All the best! / Alex
wouldnt it be that upon release, the rate at which the yard stick falls beyond the event horizon would be exponentially greater, accounting for the staggered fall? as in, the further away from the pivot point, the yard stick would travel faster, "releasing" the coins with a delayed effect.
it cant be the angle of the yard stick, it has to be the speed at which its dropped
the angle is attributed to friction, which is what would keep it in place on an inclined yard stick, and would only fall off if dropped fast enough
thats just how i see it
...is simply ,a "provocative topic" about the free fall in gravity:so many shapes,so many kind of mass distribution,different states of matter .
As Prof. Milkovic said (you know his "Two Stages Oscillator"...),we must study and undestand firstly,no more than a simply "large" pendular fall...and you can make easy tests,in the manner of Mikhail Dmitriyev...
All the best! / Alex
Hi Alex: It would be interesting to see the same experiment, but instead of coins, use a 1 lb. weight at 6" from the pivot point fixed to the yardstick and another 1lb. weight at 6" from the free end. when the pin was pulled to let the stick fall, in superslow motion it would look like the free weight was standing still, while the yardstick was accellerating away!!
Hi Dr !
Really,the first step is to study,the free gravity fall of a single mass,then of a pair of masses.
If you take a look at www.youtube.com/watch?v=FQ02MjqBk7s and there at the sequences (23-30sec),(66-100sec),you can understand me better.
With an increasing radius (diameter),we can get (and store...!) more and more energy,so to imagine a self process:the same input (unbalance),in the top position,can develop a greater and greater output ,in the bottom position...
All the best! / Alex
HI Alex: I studied free falling weights for almost a full year, My favorite setup was a 4 lb.hammer pivoting on a 30" handle free falling 90 degrees and smashing a .49 dia. lead ball. I wanted to see how much static weight it would take to get the same result. I was pretty surprised at the results.
Hi Dr !
The free fall must be correlated with the storage (rotational inertia) of gravity power,so to "pay" the friction,the "remake" of the starting unbalance and...the utilizable ("free") output supply.
All the best ! / Alex