Sarah Fox wrote: > Oops... Better late than never. I had edited this email and set it aside > in my drafts folder, rather than sending it. Then I thought I had sent > it... Oh well.. FAIW, you asked for clarifications on what I had written > in my last email... > > ----------------------------------- > > Hi Ric, > > > Sarah: I think where we're miscommunicating is that you are using the term > "inertia" in the same way that I would use the term "kinetic energy." They > are actually different. Kinetic energy has a velocity component to it, > while inertia does not. Hmmm.. before anything else how can you say that inertia does not have a velocity componet to it... F = m a.... and accelleration is change in velocity... That question posed I think what you say turns out to be probably exactly what the situation was. Tho how I came to mix up the two in this particular kind of application is another question. But I think perhaps I am not alone out there. Its hard conceptually, unless a complete enough explaination is given, to get past what we most easily see with our eyes... and in this case I suppose thats teeter totter leverage... You <<see>> that the lead on the front side of the lever makes the load lighter... and its hard to get past that.... tho really I suppose what you could say is that in a real sense what happens when you get past 9.8 m/sec^2 is that the lead more or less changes sides..... at least in the sense that it becomes just that much more mass you have to push around. It funny really, this discussion has been up several times, and this distinction as it relates to our key and key leading has not been made clear really untill now. Tho in retrospect I see that John Hartman made a really decent attempt a while back with his illustration. > > > We're also talking about collisions and mechanical coupling in different > ways. If I might, I think this is how you're thinking about the > keystick/wippen energy coupling: The finger delivers energy into the > keystick. The keystick moves. Because of its mass, it has a certain amount > of kinetic energy. Then (roughly instantaneously) the capstan delivers > energy to the wippen/hammer. The inertia of these elements provides > resistance against the capstain's motion, slowing the keystick. > Yes.. I think I undestand correctly ou here.. and If I do that fits well what I thought was happening. That the whatever inertia downwards that the key lead has was delivered upwards to the capstan and so recapturing and gaining the cost of moving the key lead in terms of how much lighter the load on the capstan was because of leverage ratios involved. I have to chew on all this for sure, and I already have a few questions that seem to jump at me right off... like just what key accelleration levels are we talking about then... If the maximum attainable speed of the key can be taken as 1m/s, then I suppose the minumum possible accelleration for that speed is 10 m/sec^2... because there is only 10 mm available to get to that speed.... which means it took us at least a 100th of a second to get up to that speed. But we probably get up to 1m/sec within the first 1mm or maybe even the 1st 10th of a mm of key travel.... which would increase accelleration by an order of 10 I suppose each time.. Also we could be talking about an instant accelleration of 1000 m/sec ^2 ??? Correct me if my figureing is wrong.... but asssuming all this is more or less correct.. then one has to ask a few things like just how much accelleration parts can tollerate... and just how much force the finger is asked to impart to reach this maximum accelleration... and then theres always.... how far into the key stroke does it take to reach any given accelleration..... what force is needed in each case... and how does our key lead vs springcounterbalance colour that whole picture. Another thought ...... stacato touch then... because that would directly use some portion of this kinetic energy... or key inertia... Anyways... I have a lot to chew. I'll get to the rest of your post this evening. Thanks muchly for all this Sarah Cheers RicB -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html
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