As far as force applied to the ball the only important parameters are mass and club head speed. In theory acceleration could make a difference because when the CH makes contact with ball and when they separate the velocity of the CH would have increases. Expressed in the following equation.
Relating Momentum to Newton’s Second Law:
Fnet = (pf -pi)/t = m(vf - vi)/t
where; pf = final momentum, pi = initial momentum, vf = final velocity, vi = initial velocity, m=mass of club, and Fnet = net force applied over a given period of time t.
However because the CH and ball are in contact for such a small period of time then acceleration becomes not relevant when it comes to force applied.
The way I see it is that acceleration through impact make the club head more stable and therefore gives more controlled and predictable results. The club head won’t have the same tendency to suddenly open, close, or shut down because of impact dynamics for slightly off centre hits. The D-plane crowd wants us to believe that impact interaction other than path and CH differential is inconsequential however there is ongoing research that is starting to show otherwise. Also, D-Plane doesn’t account for gear effect so therefore it’s an incomplete model.
You might be aware of it, the benefit is the backward flex in the shaft.
Both club heads are going 100mph
Club head constant or slowing down through impact, meaning with no ball in the way the club head would be moving the same speed or less after impact than it was before impact.
Club head is speeding up through impact, meaning with no ball in the way the club head would be moving at a faster speed after impact than it was before impact.
Club head 1 hits the ball with the energy transferred from the club head moving 100mph at impact. Club head 2 hits the ball with the energy transferred from the club head moving 100mph at impact combined with the stored energy in the shaft transferred to the ball.
Club head 2 would hit the ball farther, faster, straighter, and would not be affected by the elements as much because of longer contact with the club face from increased compression. The energy stored in the shaft is transferred to the ball at impact because the club head decelerates through impact because the ball slows it down. When the ball slows the club head down, the shaft flexes forward while the ball is on the face transferring the energy in the shaft to the ball. This creates longer face contact with the club head from the ball being compressed more, because there is more energy in the club head being transferred to the ball. This makes sure that the ball “sticks” to the club face by being compressed into the club face. The ball does not have the opportunity to slide across the club face, which decreases side spin in either direction. The result is a much straighter ball flight. Aside from the ball not sliding across the club face, the ball flight has faster acceleration in the club face direction at impact. The more the ball is compressed, the more it has to decompress. The decompression off the club face sends the ball into flight at faster acceleration, and can’t deviate because the ball is decompressing at such at fast rate in the direction of the club face at impact. The compression is the “sound” of great ball strikers, the decompression is the “bullet” flight of great ball strikers.
For more detail go into Top Threads and read Lags Holding Shaft Flex… The Holy Grail of Golf, page 1 explains. “Many say it can’t be done… I know for a fact it can…” Still my favorite page and quote on the site, put up in the office to remind me what I am constantly pursuing.