I was wrong. My first impressions were very wrong.
You really are better off ignoring me or not commenting. I will never let you forget your stupid comment about not knowing anything about tension. You still haven't told us what keeps a rubber in tension. Neither have any of the other so self proclaimed good TT players.
Everyone, go back a read the thread. I can see that only izra seems to be interested knowing the details about dwell time. At least Grandpa thought he was contributing. The rest of you are just noise.
I bowed out of this conversation some time ago but you continue to rubbish my contribution. I will make very clear my case and then I will leave again, because it would be foolish to maintain an argument with a fool, but I feel compelled to make a comment against your insults.
1) Do not listen to this guy. He is presenting you with nonsense physics and using some credentials to make them seem valid. He claims to know what he is talking about, but in fact does not. I will expand on this in a moment.
2) I also found Carl's posting of his playing ability to be in bad taste, though I agree about the point that playing ability is of importance. There are physical scenarios that only better players find themselves in, like making contact at certain angles and certain speeds and in certain body positions, and they're also generally more attentive to the play and what they're doing. However, Carl has thoroughly apologised for a small incident. Where is our friend's apology for his far more brutish and inexcusable behaviour?
3) If you want to figure out a few things about what's going on behind dwell time, I have a potential framework/model in mind with which to try and work through the problem, but this forum isn't the place for that kind of thing. If anyone is interested in trying some experiments (only school level background in science and interest is necessary) send me a PM. Could be a fun project. I have acces to all the lab equipment that we may need.
4) I agree with the comments that the details of the physics are of little use to a player, of any level, as far as improving their game goes. Subjective ideas along the lines of "touch" and grip pressure are of more value to anyone looking to improve their game.
5) If we want to crunch numbers and be able to describe the significant aspects contributing towards dwell time, the situation is somewhat complex and I suspect it is quite dependent on the nature of the rubber. We would probably have to produce a number of categories which have differing results. Things like tacky and not tacky; porous and not, and how each of these categories responds to various speeds and spins of incoming balls. For sure, using equilibrium ideas and equations you could find in the first chapter of an introductory mechanics textbook (as our friend has been using) will not solve the problem.
Our friend said "The force of acceleration is only the force due to gravity in my example above. The upwards force is due to the rubber pushing up. Since they are equal the ball stays on the rubber. In all cases the force of the rubber on the ball must be roughly equal to the force of acceleration if the ball is going to stay in contact with the rubber"
Let's take the simple case where a ball with no spin is coming towards the bat face in a direction perpendicular to the plane of the face. When a ball is incoming with speed towards a rubber, it makes contact at speed, starts deforming the rubber and burying itself into it, all the while coming to a gradual stop on the surface of the rubber, and then accelerating roughly back the direction it came in and leaving with a speed not more than the incoming speed for a stationary bat, or with a speed higher than this minimal case of a stationary bat if the player moves the bat towards the ball at impact.
This process of the ball coming in with speed, losing speed, coming to a stop, then accelerating away from the bat, implies a net force on the ball, else its velocity relative to the bat would not change. From the moment the ball contacts the rubber surface to when it leaves the surface, the ball and rubber are in contact, and yet there is no equality between the force of the ball on the bat, and the bat on the ball. This is in direct opposition to our friend's claims. And this simple model is also more representative of the situation of gameplay than the ball idly sitting on the surface of the bat with "infinite dwell" as in our friend's example.
All the best
