Scott -
You don't need high speed video to prove that any pendulum stops at its turning point, i.e., at the end of the backstroke. Of course it slows down, stops, and starts moving in the other direction. What it doesn't do unless there are extra forces is pause in the stopped position. I am more than happy to explain this in terms of Newton's Laws of Motion if you like.
But I fear the real issue here is that you guys have been teaching for a long time that
(1) there's no such thing as stroking without a pause--that everyone pauses at the end of the backstroke.
(2) that your stroking method that includes a deliberate pause is really the same thing as what the apparent no-pause pros do, that their pauses are just short.
(3) You might even tell the students things like that Newton proved there must be a pause hundreds of years ago.
If this is what you teach, then you are misleading your students in all three of these assertions.
This is not to say teaching people to stroke with a pause at the final backswing is not the best way to teach a stroke. Maybe it is. I've spectulated there are a few advantages to ingraining a no-pause stroke. But when it comes down to it this is very much a personal preference thing.
I have no doubt that you guys are effective in developing and ingraining sound stroke sequences in new students and improving the mechanics students at all levels. This discussion is not at all about what you teach students to do.
The fact is, Scott, some players pause at the end of their backstrokes and others do not. This is reality, and it's perfectly consistent with Newton's Laws of motion. I can perfectly understand your reluctance to accept this considering I now gather you have been teaching something different to students and therefore feel a need now to defend it. But if you teach the above, then you are just plain wrong. My opinion is you should stop teaching that.
A pause is when the velocity and acceleration of the cue are both zero. That means it needs to be still and also have a tendency to remain still, even if just for a short time. This is not going to happen by accident; it requires a deliberate balancing force.
A common no-pause-at-the-backstroke stroke has a nonzero acceleration when it stops at the end of the backstroke -- just like a child on a swing or the tides on a beach or the time-keeping pendulum on a grandfather clock, or a person on a bungee cord ----not a pause in sight.
