Li0nHart

Yes..we have deviated. Right now it appears I am giving out free lessons on gravitational motion.

Joel5.0

Back with the "average velocity" theory. And I am the one that needs to take physics?...... So based on pure kinematics, there are no points in which velocity in the cylinder axis frame of reference is zero, nada, zilch?

Does the piston stop in reality?... yes, it does. Does it take a coffee break? ...no.

... I keep forgetting you need everything itemized...... OK.

And the base or the rest point of the ball keeps escaping your attention...... Again..... the top of the rest point of the ball, you know, the one that was in contact with the ball at the initial point, at the same exact height in the "y" axis as the base of the ball before starting to fall, separates and starts to increase the gap (again, focusing on the "y" axis only and ignoring its gap increase in the "+x" direction). So... you have a point accelerating in the -y and x direction affected only by -g, which is the same acceleration vector the ball is exposed to yet...... the point of the base where the ball was resting, accelerates faster in "y" even though it also moves/accelerates in "x". And yes, there is a physics explanation for that.

IOW..... I know about the relative position effect when the beam rotates however, that is NOT the point. Or can't you grasp that the focus is only on the resultant motion in the vertical only?.... you know, the action axis for -g.

EXACTLY!..... yet both bodies are subjected/exposed to the same/equal acceleration..... gravity. In the same axis of action... straight down, yet the ***** support point covers more NET distance when you add the point's motion in "x" and "y" due to its physical attachment to the board. However, when you only focus on the vertical, it too increases at a faster rate..... even though they are all subject to the same acceleration constant.

..... don't you see the gap between the red lines I drew? My theories?..... again, don't you see the increasing gap between the ball and the initial rest point in the vertical axis only, even though that point also "travels" in the "x" direction when compared to the ball's motion in the vertical axis ONLY? ..... I guess not.

LOL.... that exam was done moons ago when 8-tracks still existed...... BTW.... where is the pivot of the board resting? Isn't it already on the floor?.... right on the frame of reference origin?.... or does that detail also escape your attention? Do you know what type of mechanical advantage that little detail causes on the beam?..... hang on.

OK..... question then...... why is the ball higher than the point it rested on when the board stops on the floor and measured in the vertical axis?...... you know, like.....


Could it be because it follows a simple mechanical principle that affects its dynamics due to the basic lever principle from Archimedes?...... wait, isn't that the same principle under/over-drive pulleys, gears, etc follow.... in the polar coordinate system?...... again, or did you miss the pivot point at the origin?

So that demo doesn't prove that the vertical component (as in the "y" axis) of the acceleration of the end of a hinged stick is greater than -g? And I need to take more physics?

Ok.... the net distance on the beam axis, which is a constant, it doesn't change.

.... that is actually caused by the utilization of the unilateral phase detractors due to the synchronization of the cardinal gram meters, that reduces sinusoidal repleneration.

In the vertical axis?.... nope, "negative ghostrider, the pattern is full". Again, see the whole sequence above.... not just the beginning or the missing end. The ball travels down, the beam travels down however, the beam has its own natural condition that affects the resultant net acceleration and velocity. It does have a mechanical advantage over the free falling body the ball is. Remember.... the pivot point.

If you say so..... yet you still don't see that the NET motion, as in y and x, of the rest point is longer, bigger..... yet faster than the vertical motion only of the ball.

Let me see..... allow me to use one of your conclusions/theories... "wear in the cylinder is only possible due to constant piston movement, if the piston stops, wear indications (ridges in the cylinder) are not possible"....... ..... why do valve guides, brake caliper housings, rear brake cylinders, also wear out? Don't the last two cases also show a ridge line where they stop?

And you are qualified to teach physics w/out the basic math and trig concepts? ... wow. No wonder you had to draw vertical blue lines to figure out the height gap (in the "y" axis) between the red reference lines that I drew on the frames since the beginning.

The emoticons or smileys are just something I like to use.... so.... what is its relevance to the the discussion? Or is individuality something that should also be eliminated, abolished?

Nope........ it is obvious my friend.

Do we live in the moon?.... LOL, it is also obvious you don't see the reason behind the question marks.... OK, here is a hint if you missed it above..... the vertical component (as in the "y" axis) of the acceleration vector at the end of a hinged stick is greater than -g.

.... Here we go again....... yes, the constant for gravity..... 9.8 m/(s^2), 32 ft/(s^2)...... OK. However, I thought the beam/ball model shown was at rest, so the only force is the one exerted by gravity..... is it not?

LOL.... I guess it also escapes your attention that from those primary elements in the clip, Pb (lead, 207.2 atomic weight) accelerates slower...... what about compared to Al (Aluminum, 26.98 atomic weight) and Fe (Iron, 55.845 atomic weight) right next to it? BTW.... they were NOT thrown up in the air, they were dropped from rest. Oh that's right..... I keep forgetting you're above studies made at the University of Bremen by professors in physics.

Does it escape your attention that the experiment shown partially demonstrates the same situation of the hammer vs. feather drop....... but in some cases in reverse?...... you know, the lighter elements falling faster than the heavier ones.

Anyhow...... since the change in velocity is the same for each particle (as in gravity)...... why does the resultant velocity of the "heavier" element is less, when compared to the other basic elements? Don't you see that the video clip shows the case in which the "lighter" elements are falling faster (as in not moving upwards when falling)? Oh wait..... F = ma, is that why?...... nope, the objects were dropped at rest, F = ma is the force of the object, which is proportional to the mass since acceleration is....... a constant. Or are you saying that an object of greater mass requires that the acceleration constant work overtime to change its velocity downward, when compared to the lighter elements shown, and when dropped from a position at rest?

Understanding them?..... sure.... long time ago. My apologies for trying to help. But then again, I don't think you see this little debate as "help" simply b/c it's not in agreement with your theories ...... my apologies for using physics and mechanics.

86 5.0L

nice thread, the OP is correct, IN THEORY. A piston is in constant motion, never stopping. In the real world though, TDC has such a minute 'movement' it is inmeasurable(like in a limit graph) in is perceived to the eye as a 'stop' in motion

Joel5.0

Two of the wisest men I had the opportunity to meet and thank for my existence (my Grandfather and Father).... taught me one of the most simple, basic, common sense concepts in life. When everything else fails, read the instructions manual and/or look for the definitions in the dictionaries. So.... lets use that approach then.......

Define harmonic or reciprocating motion.........

U. of Tennessee PHYSICS Dept.
The U. of Sidney, School of PHYSICS (AU)
U. of California, Dept. of PHYSICS
Wikipedia - Simple Harmonic Motion
Does a piston, in a reciprocating engine, come to a stop at TDC and BDC, in the axis of the cylinder, which controls/defines its linear motion?....

Li0nHart

I don't have time to counter every point posted but...


Well lets put it this way...

I cruise on over to my buddies house in his own car to watch the game. As I approach his house from the west I notice the cops are there busting him for something. Well knowing my friend, he probaly has 40 kilos of coke in the trunk so I proceed to keep on driving past his house and head east.

How long did I stop going west before I started going east of his house?

Even though the car never physically stops, the exact point of time that the direction change occurs can be calculated by knowing the distance to and from the center his house in each direction and how fast I was traveling. Get it?

..no stop in time = no stop. Unless you care to give me your "frame of reference" for the time of the stop...we'll need two points in time please.


This is a waste of time but anyhow....You are not going to get me on technicalities...I could go on forever with this stuff...Yes, I recalled the wrong assumption as to the location of the cup...It makes no difference to the outcome you are trying to get at though...Gravity isn't mysteriously accelerating the beam faster than should be possible.

I have heard all kinds of anti-gravity conspiracy theories present with this simple apparatus and they are all ridiculous...let me say that again RIDICULOUS!!!

I tried to keep things simple by highlighting the differences vertical distance traveled in blue as that is all you really need to look at to see what will happen...but

you press on...

On each one of these beam and cup models there is what is referred to as a "sweet spot" (there is an exact term for this, something like precession, percussion or per-something). I can't remember the exact distance out from the pivot but it is somewhere at or in the last third of the beam. Points on the beam after this point will fall greater than gravitational acceleration alone and those before will fall slower...My God!!!..how can that be!!!

Hence my original question to you.."Why is it possible for all points along the bottom of the beam to hit the table at the same time"

Which leads to the following...

Yes there is a mechanical advantage...These different accelerations occur due to a mechanical advantage around the center of gravity, center of mass, or Sweet Spot of the beam...I can't remember which one...and I really don't care to reference it right now. ie..I know if you place a weight before that particular point of the beam it will fall faster and after it will fall slower (it's counter intuitive, hence many folks have problems visualizing it)....placing weight also has the same affect as lengthening or shortening the beam.

The inclined beam/cup behave no differently than a lever, gear or pulley...Distance/speed at one end is traded off at the other side (of the center of gravity,sweet spot or whatever).

A Lever/Gear/pulley set can be used to allow a 1kg mass to accelerate a 100kg mass under the influence of gravity alone. Does this indicate that gravity has acted differently on the two objects? Of course not...If gravity truly did act differently, then we would not need contraptions to provide us with mechanical advantages.

This is the error I may have made going from memory alone, I assumed the sweet spot and the cup location were in the same spot...Now does the cup sit at the sweet spot which is equal to the downward force of Gravity. I honestly can't remember...but it doesn't matter as the cup sits at the exact spot or further out. As long as the cup sits at the intersection of the end of the beam in the vertical and it's transcribed location on the beam in the horizontal, the cup base will get under the ball. If it sits further out than the sweet spot, then the base will accelerate faster than the ball....there is a trade off, as energy and momentum must be conserved.

Now the entire beam hits the table at exactly the same time dictated by the altitude of the sweet spot in free fall since all points are aligned with this particular point when the beam goes exactly horizontal (stops). Importantly...the net result of acceleration of the entire beam is equal to 9.8ms/per second...which is the exact same speed at which the free falling ball is accelerated at.. In other words...the entire length of the beam behaves as if it were dropped horizontally from a height equal to the sweet spot.

Since all points of the beam hit the surface horizontally at the same time...some points on the inclined beam had to fall faster and some slower...energy is conserved, no additional energy was drained from the earths gravitational field to account for the increase in acceleration at the end part of the beam.......The conspiracy theorists are wrong.

The differences in acceleration are due purely to a mechanical advantage at different points on the beam and not to anything more mysterious than that.

If you believe this is an example of gravity acting differently on different bodies...ie, the ball compared to the faster/slower points on the beam...then you are sadly mistaken, as you would put it, "My Friend".

The result of all of this as per the ball and cup...The ball falls further than the base of the cup...if the cup wants to fall faster, great...but it doesn't get a free ride...my original point and simple diagram still hold true.

Does this prove that gravity acts differently on different objects Sorry...No...as there is a mechanical advantage to interfere with that theory.

I typed this up in few minutes strictly from memory...I could care less if I have missed some little point that makes no difference in the outcome...Gravity acts as it should and does nothing unexpected. There are no magical different accelerations.. They are all accounted for.

All the drivel above can be simply shortened to this...

Unless all points along the cohesive beam are accelerated above that of -g, then your theory has no leg to stand on.

...you take things to ridiculously absurd levels to prove nothing...

Umm...I never said anything like that. All I ever said was that wear will only occur where physical contact is made, regardless if a stop has occurred or not. You may have mistakenly quoted yourself.

The blue lines were for you...

Right now I'm subbing chemistry and helping students prepare for exams before summer. I still have to look things up...I'm not going to say I have all of math, physics, chemistry, Computer Science memorized through to the university levels. My basic foundations are still intact though.

They are juvenile and make your posts look stupid and hard to follow. I'm not trying to give you a lesson on grammar as I take shortcuts as well.

How is this important to this discussion?...

Well, when I see a bunch of complex terminology, diagrams, 15 different types of animated smileys, and a StarTreck video all mashed into a single run-on sentence encased in an overly large paragraph, I tend to give it as much thought as a pile of dog carp laying on the sidewalk.

I take note that it exists, then I step over it and forget it...in other words, I'm not going to bother reading it, so if you were trying to receive a response from me, you are wasting your time typing it..

If you need to include all that carp to get you point across, your point is either nonexistent or very weak. You words should be able to stand on their own...your points should be clear and concise.

Now if this were a dating site..I might feel differently.

Well we have been to the moon (not me personally) and free falling bodies are able to be attracted to it's surface, So I'll assume there must be gravity present.

I have explained above that points on the stick accelerate differently to due to dynamics associated with it's center of gravity....nothing magical occurs there...Galileo's Law of Falling Bodies remains unaffected.

If you still believe that gravity acts differently on different bodies, then explain to me why it is possible to have a feather and hammer land at the same time when dropped from the same lunar height...I find it hard to understand how you simply skip over and continuously ignore this proven fact/Law

Everyone reading this, knows there is a significant mass and material composition difference between the hammer and the feather...yet they behave the same as far as gravity is concerned.


That video is total joke...and Yes I totally disregard it in the same manner that the thick skull conspirators who believe the falling inclined beam is equivalent to an anti-gravity and free energy machine.

If I were to have that little contraption in the video physically in my possession I would quickly ascertain as to why it does what it does...and my conclusions would not involve any mysterious forces.

Since you seem to think that different elements accelerate differently under gravity. Drop a 5kg ball of lead and a 10kg chunk of Aluminum and tell us which one hits the ground first.

That should just about end that discussion.



They are not my theories... I stick within the confines of the known laws.

Li0nHart

Your Father and Grandfather are wise, I've lost many an hours work by not reading the instructions.....But I don't think you are going to find the answer in this manner. Those profs are using their words very carelessly when they say "stop". They would have been better off stating the velocity goes to zero...as that can happen without a stop.

If you feel you can, then use the above professors calculations or simply look it up in the dictionaries and tell me how long the stops occur for.

To keep it simple just use a simple projectile traveling up and down in a ballistic trajectory...fire it straight up at 90 degrees to make it even simpler.

If someone tells me and insists that something stops...they better damn well tell me for how long if I decide to ask.

Joel5.0

Gee.... I wonder why?

Was your car constrained, limited to the East - West (up - down in a piston) axis by a tunnel (cylinder)? NO. Change all the conditions for a specified condition, and you can come up with any type of analogy that suits whatever it is you are trying to explain. Or does a piston in a cylinder has the same DOF (as in Degrees Of Freedom) in motion than a car on the street? THINK!

Nobody is saying the opposite, yet you keep on ignoring the NET result. Does the point at the end of the beam accelerate faster when compared/analyzed to a similar single point of a body at the same position in the "y" axis under the same acceleration from gravity? YES.

Nobody is "anti-gravity" yet again. you seem to ignore the fact the setup of the beam causes a NET result different to the free fall model of two bodies totally suspended on a rest position over the floor.

Again, and you totally missed the fact that was already accounted for, depicted, shown, by the gap between the red lines.

...... you don't know?...... angular acceleration, angular momentum. And no, what you describe above as "made up" anti-gravity physics concepts, are NOT. That is observed phenomena (as in empirically) when chimneys fall. Or how do you think the point at 1/3 up the height of a chimney, theoretically touches the ground at the same time the tip does, even though it's higher?



Aren't you now debating with yourself? Jesus Christ..... you always end up in gravity. Here, let me make it clear AGAIN!...... gravity = acceleration vector towards the center of the earth with an approximated constant value of 9.8 m/(s^2)[32 ft/(s^2)] acting on everything on top of this great planet of ours. However, its NET effect can be manipulated/altered by mechanisms to generate motion in other directions and also affect its NET magnitude in the same direction it acts.

You seem to always go back to gravity and its constant.... again that is common knowledge..... it's the results from its manipulation and phenomena that are under scrutiny.... it's value and direction is used to explain how the tip of the beam actually accelerates faster, in the same direction of gravity, than its constant value, when the base is on a PIVOT setup. Here..... the following is a free body diagram of a falling chimney, which is similar to the beam shown..... not a car going to a friend's house, etc, etc.



How would the point at the tip travel down to the floor, and touch the floor at the same time the center of gravity of the beam (lower in the "y" axis) .... if that point doesn't accelerate faster than the gravity constant? Or do you need the free body diagram of that upper point of the beam to conclude it does accelerate faster, over the constant value of -g, yet caused by -g itself? IOW.... focus on the REAL conditions of the situation or model under scrutiny, not manipulate its setting to prove a fact that has been discussed/proven/over-proven ad nauseam..... which is..... the constant of gravity.



Why provide something that is not needed? Keep them, you can make better use of them.

Yup..... remember, gravity is an acceleration vector towards the center of the earth with an approximated constant value of 9.8 m/(s^2)[32 ft/(s^2)] acting on everything on top of this great planet of ours.

My bad then, I'm sorry for the information overload, but since you need to have everything itemized to prevent comparisons with non-relevant and totally different situations, I felt compelled to try to help. Regarding the emoticons/smileys and the dating comment........ you're barking up the wrong tree.

.... don't you see that the above is almost in complete agreement with ALL my points? At no point in this debate I have argued the value/existence of gravity. Again, it's the NET results (tip of beam accelerating faster than the ball, both under the effect of -g). Now....... the good part. If you reassign the frame of reference to the bottom of the cup, wouldn't the NET result be the same as the ball levitating and arcing into the cup? You know, another physics concept known as the coriolis effect. Or is that too difficult? Do you now see the importance of a frame of reference?

BTW.... free bodies also attract themselves, there's gravity between them, even on the horizontal axis..... or haven't you heard about Mr. Henry Cavendish?

Gee.... what a fertile neuron soil for new R&D technology and discoveries ..... .... I'll bet if this were the times of Galileo, you would be on the Aristotelian side.

BTW..... the only "mysterious force" in that experiment is simply called Nature, Reality.

If you say so.

Joel5.0

... so velocity can go to zero, AND GO AGAINST ITS OWN DEFINITION?

.... I really have to write this one down....LOL. Now it's you against the Physics curriculum syllabus? And no...... "they wouldn't have been better off"....... your "argument" would....... sorry that's not the case.

It stops in the vertical when Vy = 0..... and?

In the projectile sample, and the real world, it stops for the time it takes gravity to counteract the momentum of the mass of the projectile in the vertical and cause the gravitational acceleration to start increasing velocity in gravity's direction. Or don't you also know that you can physically stop a body moving on a specific frame of reference, release it, and it will continue moving in the same direction you stopped it from moving? Does that go against the concepts, laws, principles of physics?.... NO. But to understand that phenomena, you need to go past the knowledge of the constant for gravity. If you don't accept that reality, no one can for you. Do you get it?

And here's another "physics conspiracy" sample case, even though physics explains it quite well...... and yes, including the existence of the constant of gravity + harmonic motion.

http://www.youtube.com/watch?v=H6nwV9bInJA

Or don't you see how gravity (and using Galileo's results from his experiments of a ball on an inclined plane) is used to defeat its own effect?

89gt347

The piston does stop... when the velocity=zero (as previously stated many times). Assuming that there is no connecting rod stretch or compression, the piston is only stationary for that split second that the velocity=zero and the piston changes it's direction (but there is stretch and compression of the con. rod).

"Dwell" is somewhat loosely used to describe the time that the piston is at top dead/bottom dead center. Because there is such a rapid deceleration as the piston approaches tdc/bdc, it makes it appear that the piston actually stops for some measurable amount of time and some measurable amount of crank rotation. "Dwell", in this case, is considered how much time or how many degrees of crank rotation the piston spends close to tdc/bdc. How close? Depends on what an individual's definition of close is...

minnow81469

i dont understand why you think the piston doesnt stop it has to come down therefore it has to stop because it changes in direction if it didnt stop at tdc then the whole engine would be in a million pieces