Shaft said:
For the same force applied over the same distance (arm muscle energy input), a light cue will have a faster speed than a heavy cue, and they both will have the same kinetic energy. A lighter cue transfers a higher percentage of that energy to the CB.
This is true, and this discussion has strayed a bit because I was trying to explain one subject that was related, but not on point.
What I was looking to discuss in this light cue vs. heavy cue discussion has more to do with what happens
after the cue ball is hit, than what happens at the moment it is hit.
A lighter cue, while it may be transferring a higher percentage of energy, will still slow down dramatically faster than a heavier one. It has less energy available for follow through, and that effects certain things like english/draw/etc. I believe this is also what Dennis was talking about with his term "Bouncing off effect" - A lighter cue will transfer the energy so quickly to the cue ball (just like your stop shot example), that, after impact, it is going
slower than the cue ball, and thus is no longer in contact with it. That's also why someone using a ligher cue needs a different grip/stroke to get the same action on the cue ball.
A heavier cue will have more momentum and "Follow through". Since it's not decelerating as much, it stays in contact with the cb longer. This also has an effect on english/draw/etc, and is why someone using a heavier cue can grip the cue lighter and have the cue's momentum aid the follow through of the stroke. Again, I'm not sure if I'm expaining this phenomenon correctly, but I hope you get my point.
I think what we're getting at here is what you said above.
Both cues have the same
kinetic energy. A heavier cue has more momentum though, and can transfer that
through the cue ball instead of just stopping at the cue ball. Kind of like the wiffle ball vs. bowling ball theory. So what I've been saying (and obviously not doing a good job of it!) is that the momentum of a heavier cue is greater (with the same force), so a heavier cue does more work.
That is what I intended the discussion to be about. Sorry if it didn't come across that way though.
In other words, the difference in what happens to the cue ball, happens after the cue goes through it, not just hits it. That's probably also why players report it's easier to do things like draw the cue ball with a heavier cue, since follow through is a major factor in that.