Theory of Technique is Dead

[keyboardclass]

Gosh, this is an impressively badly-argued debate. Does anyone have a clue what any of these posts is on about, beyond the absolute outline basics?

Obviously.  My videos!

[richard black]

Obviously.  My videos!

You mean the posts are about your videos? The argument about pushing a pram is about your videos? I was looking for rather more detailed explanation - but never mind, I'm only browsing in an idle moment as a work-avoidance strategy, I'm not really all that interested, if I'm brutally honest.

[keyboardclass]

By the way I sent you a PM.

[nyiregyhazi]

Obviously.  My videos!

personally I'm more interested in the nature of possibiility in technique, but your videos are an excellent example of what happens when a person models energy transfer upon fixing the arm like a stiff stick.

What I find baffling is that you take offence when anyone points out how stiffly you move in your videos. But then you spend a thread arguing in favour of turning the arm into the equivalent of a stiff stick? What are you hoping to prove? Your own analogy shows how much less efficient it is to create a stiff structure, rather than use the range of joints in movement. Nobody would hope to accelerate a pram to a high speed with a fixed arm, rather than one that is being extended to instigated motion.

[keyboardclass]

What I find baffling is that you take offence when anyone points out how stiffly you move in your videos.

Apart from you, nobody does.  It's just your ad hominem way of dealing with the lack of support for your bizarre views.  You can't play the ball so you play the man.

[venik]

Oh dear. So the implication is that the stiffer your arm the better? What you have forgotten is that the arm is neither one singular rigid solid structure or one singular floppy structure.

If I straighten my thumb into a key (without any muscular pressure from the arm), it's neither stiff nor floppy. It's just moving naturally. However, it offers zero scope for loss of energy transmission into collapse (without requiring muscular seizure). There is only movement, not stiffness. This low effort motion can make for a very big sound, with very low impact and stress (although it takes time to develop the thumb muscles for a really big tone). There's nothing else between the energy source and the key that could ever buckle in a way that would compromise acceleration. It's travelling the other way.

How about if we use our arms to push the pram? Would you start with a rigid arm? Not exactly a great way to achieve acceleration- even if the arm succeeds in being as flawlessly rigid as a block of steel. Or would you use an action that eliminates the give in the joints simply by initiating movement- hence no requirement of fixation? If something is moving one way, it can't double back. Plus it contributes acceleration by moving. It's possible to achieve the closest thing possible to lossless transmisison without a single fixation occurring.

I can't believe how lost you are. A non-rigid structure cannot push anything. And things are either rigid or non-rigid, not "neither." Now we are getting into your lack of logic.

As your arm unbends to push the "pram", it is a collection of rigid objects. Your hand, your forearm, and your upper arm. Your upper arm extends the forearm, and your forearm extends the hand. If you were to keep your forearm still and just use your hand...then your forearm's weight is excluded from the mass of the movement. It needs to move to have momentum.

You can push a pram as well as any other with a straight arm, you just need to other means for the energy as your arms have no mechanical advantage anymore. Your legs would work.

Your arguments seem to be based on an alternate reality that you have created where things work just the way "nyiregyhazi"'s intuition believes they should work. This approach to science doesn't result in any sort of scientific conclusions.

Nyiregyhazi has been pming me, I think in attempt to intimidate me into stopping this embarrassment of his understanding of physics.

[thalbergmad]

Gravity, pushing prams, hitting balls with bats, kinetic energy!!!!!!!!

Sometimes I wonder if I am actually in a piano forum.

For sure, I am glad that I don't understand most of these posts and I would not spend time trying to. I am off to play Steibelt which is of far more use.

Thal

[nyiregyhazi]

"I can't believe how lost you are. A non-rigid structure cannot push anything. And things are either rigid or non-rigid, not "neither." Now we are getting into your lack of logic.

As your arm unbends to push the "pram", it is a collection of rigid objects. Your hand, your forearm, and your upper arm. Your upper arm extends the forearm, and your forearm extends the hand. If you were to keep your forearm still and just use your hand...then your forearm's weight is excluded from the mass of the movement. It needs to move to have momentum. "

Have you honestly not realised that (aside from the first paragraph containing yet another definably inaccurate assertion) those paragraphs of writing are in utter contradiction? Rigid in physics is defined as meaning that any two points stay at constant distance. A moving arm is not a rigid structure. Neither is any single joint of it- when they are all either moving or freely movable in response to force.

 It's all very well being hell-bent on arguing with me at any cost, but can you please check your facts before proceeding to "correct" me with fallacious assertions? An arm is a non-rigid structure (unless joints are locked) yet it pushes that pram just fine. So your assertion is disproven by counterexample. Stop inventing your own scientific laws! Sure, the bones are rigid (not generally subject to human control- if you thought I was advising letting the bones go all bendy) but the arm is not and neither is a single joint of it unless you make it so with severe muscular co-contractions. Fair point that the arm is either rigid or not. What I am referring to is that the arm certainly has far more states than simply rigid or limp- despite the fact that you made arguments assuming these to be the only possibilities. It's not a situation with only two possibilities. Joints are not "on or off".

You cannot correct that which is not in error (especially not with assertions that are), no matter how pedantic you would like to be towards me.  
"
You can push a pram as well as any other with a straight arm, you just need to other means for the energy as your arms have no mechanical advantage anymore. Your legs would work. "

Or you could use both. It would be a vastly less effective technique to try a stiff arm and restrict acceleration to the legs alone. Go and find a pram and try it.

Anyway, I'm glad to see that you have stopped making those remarkable claims that Newton's equation for calculating kinetic energy is supposedly based on changes in velocity.

[venik]

Have you honestly not realised that (aside from the first paragraph being a factually inaccurate assertion) those paragraphs of writing are in utter contradiction? Rigid in physics is defined as meaning that any two points stay at constant distance. A moving arm is not a rigid structure. Neither is any single joint of it- when they are all either moving or movable in response to force. It's all very well being hell-bent on arguing with me at any cost, but can you please check your facts before proceeding to "correct" me with fallacious assertions? An arm is a non-rigid structure (unless joints are locked) yet it pushes that pram just fine. Your assertion is hence disproven by counterexample. Sure, the bones are rigid (not generally subject to human control- if you thought I was advising letting the bones go all bendy) but not the arm is not and neither is a single joint of it unless you make it so with severe muscular co-contractions. The arm has far more states than simply rigid or limp- despite the assumptions you made in a prior post.

You cannot correct that which is not in error (especially not with assertions that are), no matter how pedantic you would like to be towards me.  

Rofl about the part where you say you are uncorrectable.

Anyways by your definition of rigid, not even solid steel is rigid. Have you ever stood under a skyscraper? They are built to bend. Physics becomes useless without this acknowledgment. There are different levels of rigidity, sure. But to say that the arm is not rigid nor non-rigid is a complete contradiction in logic. Then the object must not exist in that case. To apply physics of rigid bodies, which is for all practical purpose what a arm is, to piano you must use that which is rigid. As an engineer I know that this calculation is always going to be slightly off depending on the scenario and application. We try to get it as accurate as possible but that's all we can do. That said assuming the forearm is rigid is going to give you very accurate results, unless we start talking about breaking arms and whatnot. There is going to be a margin of error depending upon how much the forearm bends independently but it will be incalculable and such a small margin of error it doesnt really matter at all.

Or you could use both. It would be a vastly less effective technique to try a stiff arm and restrict acceleration to the legs alone. Go and find a pram and try it.

In your scenario you didn't use both, and I venture to say the legs would do a better job by themselves than arms would by themselves. Being that the strongest muscles in the body are in the legs.

Anyway, I'm glad to see that you have stopped making those remarkable claims that Newton's equation for calculating kinetic energy is supposedly based on changes in velocity.

I still claim them, just not in my last post.

I think this assertion of yours comes from your lack of reading comprehension. This one's for you:

Calculating *work* is dependant on acceleration.

Why did I say that? Well I have no idea, besides the fact that if I dont it appears to you that I submitted to your flawed logic.

[nyiregyhazi]

"Rofl about the part where you say you are uncorrectable."

Yet another strawman? I said that you cannot correct something unless it is in error. That's a statement of fact, not a boast of personal infallibility. Whenever somebody corrects me (accurately) I'm more than willing to hold my hand up. Who would want to base a study of possibility on bogus data? It would be simply deranged.


"To apply physics of rigid bodies, which is for all practical purpose what a arm is, to piano you must use that which is rigid."

You missed the bit where I said I don't want to apply physics of rigid bodies to the arm as a whole, or use my arm that way? The bones are rigid anyway. We do not control that variable. So what on earth is that point supposed to imply, in practise? What is the relevance of stressing that the bones within a structure are rigid beyond control when the structure is not? Not one joint needs to be rigid, as long as they are moving in a way that positively aids acceleration, rather than collapsing in a way that hinders it.

"In your scenario you didn't use both, and I venture to say the legs would do a better job by themselves than arms would by themselves. Being that the strongest muscles in the body are in the legs. "

Active input of energy from the legs or not, a straightened and rigid arm is a poorer way to accelerate the pram than an arm that activates into motion. Buy a pram and see, if you don't trust the mechanics.
 


"Calculating *work* is dependant on acceleration.

Why did I say that? Well I have no idea, besides the fact that if I dont it appears to you that I submitted to your flawed logic."

I have to point out yet again that I was referring to YOUR calculations? How was I even supposed to calculate the work done when YOU presented an instantaneous velocity without reference to the time it took to reach it? Stop trying to being a pedant. If you argue based on emotions rather than out of interest in the topic, you'll just end up making more blunders.

I have not the slightest interest in the net work done anyway- as long as I'm not wasting too high a percentage on impacting the keybed. When's the last time you felt out of the breath or in dire need of a lucozade from piano playing? If I worried about expending another calorie or two, I wouldn't go to the gym. If there's not a large amount of energy landing hard in the keybeds, I don't give a damn. Even if your calculation about four times the kinetic energy had not been reached by both leaving out a collision and misusing an equation, that would be fine by me. I don't count calories when I play the piano.

PS. I look forward to being "corrected" for referencing calories instead of Joules- despite the fact that both are valid measurements of energy.

[venik]

Yea uh, just ignore the most crucial part of every post. The last one being that the arm in motion is a collection of rigid bodies which can be explained by rigid-body physics.

I guess you kind of just said "i dont want to"?

I said I don't want to apply physics of rigid bodies to the arm as a whole, or use my arm that way?

[nyiregyhazi]

Yea uh, just ignore the most crucial part of every post. The last one being that the arm in motion is a collection of rigid bodies which can be explained by rigid-body physics.

So, what? It does not follow that the arm itself is a rigid structre. Neither does it follow that any of the joints need to become rigid to transfer energy. Who denied rigidity of bones? Another strawman for you? We have no control over the rigidity of bones. What is there to even discuss? Are you suggesting I might accidentally allow my bones to go slack if I'm not careful? If not, can you please enlighten me as to what you are arguing about? The variable we control is the muscles and how they cause joints move/rigidify. There's no need for the latter if they simply move instead.

[venik]

I have not the slightest interest in the net work done anyway- as long as I'm not wasting too high a percentage on impacting the keybed. When's the last time you felt out of the breath or in dire need of a lucozade from piano playing? If I worried about expending another calorie or two, I wouldn't go to the gym. If there's not a large amount of energy landing hard in the keybeds, I don't give a damn. Even if your calculation about four times the kinetic energy had not been reached by both leaving out a collision and misusing an equation, that would be fine by me. I don't count calories when I play the piano.

Actually I guess this is kind of the first relevant paragraph you've had...sorry i missed it.

Well it does matter how much work you are doing compared to how much of it is effectively playing the key. This is the difference between playing at 50 bpm and playing at 150 bpm. Using the power available to you effectively. It's not about prowess but technique. I.e. how much energy can your muscles put out in a given time and using that to it's full potential by playing more keys with that same amount of energy (and properly and voiced etc.). In your pressing away method, by my understanding, your using the same muscles on the up and the down movement essentially cutting this efficiency in half.

[venik]

So, what? It does not follow that the arm itself is a rigid body. Neither does it follow that any of the joints need to become rigid to transfer energy. We have no control over the rigidity of bones. Are you suggesting I might accidentally allow my bones to go slack if I'm not careful? If not, can you please enlighten me as to what you are arguing about?

By tensing them you are turning two rigid bodies into effectively one, likewise if you ducttapped two sticks together. Albeit muscles cannot create the rigidity of bones, they can connect their momentum from the upper arm to the end of the lever, the hand. In the case of the sticks for example, the more force put on these connections the more force is needed counteracting by the ducttape. Thus if you are to grab on of the sticks and press on something with the other, you might as well have grabbed the stick that is actually touching the thing you are pressing on. Because like in the arm, much energy is simply wasted transferring the momentum from the upper arm to the finger. It's better to simply use the finger, when possible. Sometimes you need the energy from the upper arm for louder sections.

[nyiregyhazi]

Because like in the arm, much energy is simply wasted transferring the momentum from the upper arm to the finger. It's better to simply use the finger, when possible. Sometimes you need the energy from the upper arm for louder sections.

I agree entirely. This is what I've been saying throughout (aside from the last sentence, although I in no way disagree with that either). But even when using the upper arm, nothing needs to be rigid. You simply need to match the force that destabilises and hinders acceleration. Or you can even allow the joints to move-  the alternative is not only to go rigid.

For example if you drive forward so the wrist goes up, you can transfer much energy and redirect momentum into that after the keybed. However if you lift the wrist and collapse it down to play, it's pulling energy AROUND the finger on key and hence sending pointless levels of momentum into the keybed- without putting much into the hammer at all. Such issues of efficiency are of key relevance. Many pianists only use fixation and others allow the joints to move in a counterproductive direction. Neither aids efficiency- so it often leads a lot more input momentum to compensate (meaning more energy going into the keybed but less sound).

[nyiregyhazi]

In your pressing away method, by my understanding, your using the same muscles on the up and the down movement essentially cutting this efficiency in half.

By pressing away, I am preventing acceleration being harmed by negatively contributory collapses of joints. They all move in a way that aids high-efficiency transfer of momentum- without need to stiffen. Try the thumb straightening action I described. Nothing can possibly be lost into dead slack. It's the need to compensate for dead slack that so often leads to fixation. People fixate to stop the energy loss caused by slack. Simply feel the thumb straightening (in the opposite direction of the motion that occurs in collapse) and you eliminate both the slack and the need for compensatory fixation.

Also, the hand may not rise a jot in the end. If the knuckles are already high they simply end up staying there. However, intending to allow the hand to be lifted in response gives you the means of absorbing the reaction force. And by thinking upwardly, you stop the arm wanting to press down.

You literally go up if you do this on a table. But on the piano the key descends- often cancelling the upward movement of the hand.

[keyboardclass]

Gravity, pushing prams, hitting balls with bats, kinetic energy!!!!!!!!...For sure, I am glad that I don't understand most of these posts and I would not spend time trying to.

That is very mucn N's strategy.  He's got into his head that you can push things with the equivalent of a damp dish cloth - this idea he clothes in obscure psuedoscience so you'll shy away from questioning it.

[keyboardclass]

By pressing away, I am preventing acceleration being harmed by negatively contributory collapses of joints.

Pressing away!?  Isn't that called pushing?  The rest - Mechanics in Wonderland.

[nyiregyhazi]

That is very mucn N's strategy.  He's got into his head that you can push things with the equivalent of a damp dish cloth - this idea he clothes in obscure psuedoscience so you'll shy away from questioning it.

This is your problem You think that there's only a rigid arm or a damp dishcloth. What matters is that there's no slack that can collapse, between the source of energy input and contact. That would be like playing through a sponge. But if a thumb extends through the key, removing all possible slack simply by moving, there's no need to brace anything. The other joints have no need to stiffen because there's no energy being sent through them to start with.

Why do you take offence when people point out how stiff you are while playing? Shouldn't you be proud of how rigid you have made your arm, if you sincerely believe that tripe about the importance of fixation? Why the hypocrisy? Instead of preaching such transparent nonsense about the value of rigid joints, why don't you stop and think for a second? You don't even believe that, if you're honest with yourself. To seize up a joint to prevent collapse is the most amateurish error in the whole of piano technique.

And yes, this action is indeed a type of push. Who's making a secret of that? But it's not a push of the whole arm. It's a big distinction, because to most people if you just refer to a "push" the whole arm push is exactly what they will do- sending far more energy at the keybed.

[keyboardclass]

This is your problem You think that there's only a rigid arm or a damp dishcloth. What matters is that there's no slack that can collapse, between the source of energy input and contact.

...and that state we call rigid!

[nyiregyhazi]

...and that state we call rigid!

That's what you tell your students? Be more "rigid"? Don't be such a bloody fool. Rigid is IMMOVABLE i.e locked up into severe co-contraction. Something that is in the act of moving is not rigid. Only the bones are rigid.

[keyboardclass]

Rigid is IMMOVABLE 

Exactly!  by the opposing force (in this case a pram).  If the stick is less rigid than the pram (like it has a hinge) it bends, if it's more rigid than the pram the pram moves.

[nyiregyhazi]

Exactly!  by the opposing force (in this case a pram).  If the stick is less rigid than the pram (like it has a hinge) it bends, if it's more rigid than the pram the pram moves.

Not if it is MOVING! Do none of your joints have the capacity for movement to occur via the muscles that control them? Stop trying to speak for the limits of possibility and recognise the simple fact that YOUR inept approach involves stiffness and fixation but that there is ANOTHER way that does not. When I push a pram (accelerating it into being released, like the hammer), I do not lock a single joint of my arm into being immovable. Every joint MOVES to contribute to acceleration- particularly the elbow.

Did you ever play any sports at school? I'm guessing that you were the type of kid who held the cricket bat rigidly and tried to swing an already straightened and very stiff arm (locked at the elbow) with a swipe from the shoulder? Perhaps you're also going to give us your pearls of wisdom about how cricketers have to lock their elbows into immobility? They don't. They use the joint to contribute MOVEMENT.

[nyiregyhazi]

Are you perhaps forgetting that a piano hammer is accelerated into a release by a short burst? If you're thinking of a leisurely stroll around the park, your analogy has no bearing. It only works for a short burst of acceleration followed by almost instant release of the pram.

[keyboardclass]

Are you perhaps forgetting that a piano hammer is accelerated into a release by a short burst? If you're thinking of a leisurely stroll around the park, your analogy has no bearing. It only works for a short burst of acceleration followed by almost instant release of the pram.

In which case we're back to the analogy below.  The Ball attached to the string just isn't going to move the pram.  And I'll repeat: If the stick is less rigid than the pram (as in the  hinged example) it bends, if it's more rigid than the pram the pram moves.  And that's your mistake isn't it?  You don't see there are levels of rigidity.  Even blancmange is rigid enough to move something!

Rigidity, also known as "stiffness," is generally measured using Young's modulus. It can be defined as the "force necessary to bend a material to a given degree."

So you see you're right! I do 'involve stiffness' when I play! (as must all)

[nyiregyhazi]

Spoken as if I hadn't already explained this? The bones are the only rigid thing. And seeing as they CANNOT be anything other than almost 100% rigid we have no need to think about rigidity (in case you think anyone needs to be careful not to let their bones go bendy). As we have already covered, if the stick has joints in it (joints that can be straightening to move the pram far more effectively than with a stiffly inert stick). there is no requirement of rigidity to brace the joint, but simply of positive movement. A joint which is moving in the right direction is not collapsing. A joint that is straightening is not bending.

Stop repeating things that we have already been through.

[keyboardclass]

As we have already covered, if the stick has joints in it (joints that can be straightening to move the pram far more effectively than with a stiffly inert stick). there is no requirement of rigidity to brace the joint, but simply of positive movement.

Here is the stick with a joint (hinge) again.  Notice it collapses as soon as it touches the pram (which therefore won't move)


And here you'll see the dishcloth is not rigid enough to displace the keys but is rigid enough to displace the water in the bowl.  So here's a new physic law for you - ALL THINGS THAT DISPLACE OTHER THINGS ARE RIGID.

 

[nyiregyhazi]

So, where are the bones in the dishcloth? And where are the internal forces that are straightening it out? If you want to use analogies, stick to the one about the straightening stick. At least it's faintly comparable to the situation.

Bones are rigid ANYWAY. The muscles do not need to be. Causing movement can remove the requirement altogether. Rigid joints are a very unsophisticated way to transmit energy. And where does your "relaxed hand" come into this?

[keyboardclass]

So, where are the bones in the dishcloth?

The bones are there when it displaces the water and not there when it attempts to displace the keys.  Get your head round that one!

[nyiregyhazi]

The bones are there when it displaces the water and not there when it attempts to displace the keys.  Get your head round that one!

I cannot even begin to get my head around why you feel a dishcloth that has no bones to hold it together is comparable. The entire dishcloth collapses. Due to bones, only the joints in the arm can collapse. If they are moving in the opposite direction to that of collapse, they cannot collapse either.

This is the single stupidest line of argument I have ever heard. Where does your "relaxed hand" come into this?

[keyboardclass]

I cannot even begin to get my head around why you feel a dishcloth that has no bones to hold it together is comparable. The entire dishcloth collapses. Due to bones, only the joints in the arm can collapse. If they are moving in the opposite direction to that of collapse, they cannot collapse either.

You are stuck with the faulty concept that 'rigid' is somehow absolute.  There is no such thing as rigid only levels of rigidity.  A dishcloth is rigid compared to a bowl of water, a keyboard is rigid compared to a dishcloth!

[nyiregyhazi]

You are stuck with the faulty concept that 'rigid' is somehow absolute.  There is no such thing as rigid only levels of rigidity.  A dishcloth is rigid compared to a bowl of water, a keyboard is rigid compared to a dishcloth!

A dishcloth is not remotely "rigid" in either situation. There is simply a negligible force acting upon it when it contacts the water (a force that barely transmit through the cloth as a whole to any degree at all). By your logic, you could say that a blancmange is "rigid" when a gnat lands on it. It isn't. Also, this is now mere semantics- with no relevance to pianism.

[keyboardclass]

By your logic, you could say that a blancmange is "rigid" when a gnat lands on it. It isn't. Also, this is now mere semantics- with no relevance to pianism.

Rigidity, also known as "stiffness," is generally measured using Young's modulus. It can be defined as the "force necessary to bend a material to a given degree."

It's not my logic it's the Laws of Physics!

[nyiregyhazi]

It's not my logic it's the Laws of Physics!

You dare to claim that the laws of physics define blancmange as rigid? Stop acting like a fool.

Even if we look at semantics, rigid typically refers to the impossibility of movement. Not the lack of it- but the IMPOSSIBILITY of notable movement occurring. Is that a good way to think? It leads to co-contractions that ensure there's no possibility of movement.  

Swing your arm around without letting your wrist collapse. Do you think of your wrist as "rigid" to keep it aligneed? Tell anyone to think that way and you can guarantee they will be bracing it with unnecessary muscular force. It's far better to perceive the minimum effort to keep it aligned than to think of rigidity.

You don't even believe what you are arguing for, so don't expect any further replies.

[keyboardclass]

You dare to claim that the laws of physics define blancmange as rigid? Stop acting like a fool.

The Laws of Physic claim nothing as rigid - that's your claim.  The Laws of Physics claim levels of rigidity (including blancmange).  You just can't get your head round that can you?

[nyiregyhazi]

The Laws of Physic claim nothing as rigid - that's your claim.  The Laws of Physics claim levels of rigidity.  You just can't get your head round that can you?

 The level of rigidity is based on resistance to notable deformation despite the onset of forces. Just because it's a sliding scale does not make a blancmange "rigid". Ability to move a very small amount in response to a tiny force does not bring anything out of the lower end of the spectrum. A joint is rigid when it's unmovable in response to various forces. Rigidity is not a quality of a joint that is being MOVED by muscles- any more than it describes a blancmange.

Go and tell all your students to be more "rigid". I'm sure they'll thrive.

[keyboardclass]

The level of rigidity is based on resistance to notable movement despite the onset of forces. Just because it's a sliding scale does not make a blancmange "rigid".

Do you know I can sense there's a gnat out there called nyiregyhazi vociferously arguing how 'rigid' blancmange is.  I suggest you stop using the word and go for 'levels of rigidity' instead.

[nyiregyhazi]

Do you know I can sense there's a gnat out there called nyiregyhazi vociferously arguing how 'rigid' blancmange is.  I suggest you stop using the word and go for 'levels of rigidity' instead.

YOU are the fool who is arguing things should be rigid! I'm the one who said it's not required and should not come into it. You are so intent on trolling that you cannot even keep track of what you are trying to argue in favour of? Which of your own theories are you going to argue against next?

[keyboardclass]

YOU are the fool who is arguing things should be rigid! I'm the one who said it's not required and should not come into it. You are so intent on trolling that you cannot even keep track of what you are trying to argue in favour of? Which of your own theories are you going to argue against next?

I am arguing there is NO SUCH THING AS RIGID!  It's all relative (as the great man said) levels of rigidity.  So resorting to your usually trolling accusations eh?   You must be getting onto the back foot!

[nyiregyhazi]

I am arguing there is NO SUCH THING AS RIGID!  It's all relative (as the great man said) levels of rigidity.  So resorting to your usually trolling accusations eh?   You must be getting onto the back foot!

From the post in which you personally brought up rigidity:

Notice the muscle's job is to keep the stick RIGID i.e. not allow the hinge to bend.

I have nothing more to say in response to such tedious, hypocritical trolling. You've come full circle and are arguing against yourself.

[keyboardclass]

From the post in which you personally brought up rigidity:

Notice the muscle's job is to keep the stick RIGID i.e. not allow the hinge to bend.

General talk.  When talking in physics one needs to say 'keep the stick fixed with the level of rigidity required to overcome the inertia of the pram's mass.'  Quite a mouthful but scientifically accurate.  So fine, we can can any talk of 'rigid'.

[nyiregyhazi]

General talk.  When talking in physics one needs to say 'keep the stick fixed with the level of rigidity required to overcome the inertia of the pram's mass.'  Quite a mouthful but scientifically accurate.  So fine, we can can any talk of 'rigid'.

Or, of course, you can simply move the joint instead- to provide a positive input without any danger of fixation or collapse.

[richard black]

I know you guys are just arguing for the fun of having a pointless argument, but even so I can't resist pointing out that:

When talking in physics one needs to say 'keep the stick fixed with the level of rigidity required to overcome the inertia of the pram's mass.'  Quite a mouthful but scientifically accurate.  So fine, we can can any talk of 'rigid'.

you can simply move the joint instead- to provide a positive input without any danger of fixation or collapse.

are both meaningless drivel.

[nyiregyhazi]

I know you guys are just arguing for the fun of having a pointless argument, but even so I can't resist pointing out that:

are both meaningless drivel.

"you can simply move the joint instead- to provide a positive input without any danger of fixation or collapse."

What this means is that a joint need not be held stiffly when you move from there. For example, when an elbow straightens while pushing something- providing an energy input in doing so. Were the energy to be sourced further back (eg. in the legs) the elbow would buckle and collapse were it not braced. This is not an issue when it's where you push from it. Hardly meaningless.

[thalbergmad]

I managed an entire Steibelt sonata last night without a thought for my bracing elbows

[lostinidlewonder]

..... meaningless drivel.

I think it would be appropriate to rename the thread to this.

[keyboardclass]

Or, of course, you can simply move the joint instead- to provide a positive input without any danger of fixation or collapse.

Don't know what that means. 

What this means is that a joint need not be held stiffly when you move from there.

Remember:

Rigidity, also known as "stiffness,"

If you are still fixated on 'rigid' or 'stiff' having an absolute value then your physics is bogus.  You need to sort that out first and maybe stop using those terms without a qualifier.

[keyboardclass]

Guys, if you've learnt nothing from reading this thread then you're certainly the lesser for it.

[nyiregyhazi]

Don't know what that means.  Remember:If you are still fixated on 'rigid' or 'stiff' having an absolute value then your physics is bogus.  You need to sort that out first and maybe stop using those terms without a qualifier.

I didn't bring these terms in. You did- when you insisted an arm must be rigid. You already seem to have forgotten that the idea that it's a lot more complex than being rigid or limp was exactly the point I made to you in response? As far as I'm concerned, reference to something being "rigid" shouldn't even come into the picture to start with. Please stop to apply the above rationale, next time you're thinking of suggesting that an arm must be necessarily "RIGID" (your capitals) to apply energy to a piano. You're arguing against the very stance you presented, once again.

[keyboardclass]

I didn't bring these terms in. You did-

stiff=rigid again:

Rigidity, also known as "stiffness,"