Heavier cue for breaking?

[Andrew Manning]

Dang.

I just hit the darn thing then run em out.

Me too, except I screw up the run-out at the worst possible time.

And then I have extremely non-practical physics debates on AZ, where the end result was posted before the debate even really got started: "it all comes down to personal preference". And I have fun doing it.

-Andrew

 

[jsp]

That is to say, there's sufficient evidence in both the real world and by physics to dismiss the simple saying "lighter is better because you can get a higher velocity" as nothing more than a simple saying.

I read Ron Sheppard's paper more extensively, and I have one big problem with his physics. Well, it's not really his physics or math that I have a problem with, but one of his assumptions.

First, look at his equation for total kinetic energy (T) on page 23. The total kinetic energy is split into two parts...the kinetic energy of the forerarm (Tf) and the kinetic energy of the stick (To). He mentions that for a fixed force and forearm length, the total kinetic energy will be the same. I agree 100% so far.

But then on Problem 3.3 and his discussions on p.23-24, he states that only the cue stick energy (To) matters at impact? How so? What happened to the mass and kinetic energy of your forearm? Are you throwing the stick at the CB, such that you're totally letting go of the stick right before impact? No, you are still holding on (for many, very tightly) to the stick up and through impact with the CB. Therefore, the mass and kinetic energy of your forerarm should still have some effect on the CB.

It does make sense that in order to optimize the cue stick energy To for a fixed total kinetic energy T, then you'd want to increase the mass of the stick (in relation to your forearm mass)...BUT ONLY if you're throwing your stick at the CB! Because you are not throwing the stick, the total energy T, not To, should be used in P3.3. Thus the effective cue stick energy should be the same regardless of cue weight.

In the first paragraph of p.24, he explains his fundamental tradeoff. A lighter cue stick would achieve the highest transfer of energy from cue stick to cue ball. However, a heavier stick would maximize the stick energy for a fixed total energy during the stroke. He then combines the two competing equations and solves for a sweet spot. However, because he's assuming you're letting go of the cue before impact, then there should be no added benefit in increasing the weight of the cue. Therefore, the physics does say that lighter the better! Let me know if I'm just crazy.

 

[jsp]

failed to read first section of chapter

Okay...maybe I am a little bit crazy. I failed to read the last paragraph on p.21 that explains Shepard's reasoning why he doesn't involve the hand/forearm during impact. He explains that the stick/CB impact time is so short, that at the moment of impact the stick slows down and starts moving slower than the hand. By the time the skin on your hand tightens to exert additional force on the stick, the impact time is over the CB already left the tip of the cue stick.

I can understand his reasoning, but my gut feeling is that you cannot totally ignore the mass/kinetic energy of your forearm at impact. Although I would agree not 100% of the forearm's kinetic energy will be felt by the CB (since your hand and the stick are not completely fused together), I don't think it is an accurate approximation assuming that 0% of your hand/forearm energy is felt by the CB.

Still, even with his assumption, his calculations still seems to favor the lighter end of the cue spectrum. If you assume that even a fraction of your forearm's energy will be felt by the CB (instead only the stick energy), then this will only shift the "optimum" break cue weight even further to the lighter end.

 

[Icon of Sin]

I dont know what to think. My father uses a 21oz breaker and a 19oz player.

My Bob Frey playing cue is 19oz and my X Breaker is 18.75, just slightly lighter. I seem to like it thi way.

Along the lines of physics and stuff like that. I dont even have an opinion, I suck at all that stuff.

 

[Jaden]

Ideally you do want to let go of the cue.

Ideally you want to kind of let go of the cue at impact even on the break.

If you are holding tight onto the cue at impact then your forearm's mass will be a factor, but that raises your lack of control over the stroke and therefore your CB control and the force that is directly appled to the foreball.

The more control you exert over the CB and the more direct the CB's contact with the OB the more force is directly applied to the OB and therefore the entire rack.

How much control and how much speed you want is going to be dependent on what you are confortable with. You obviously wouldn't want to break with a medium stregth hit to have greater control, but you don't want to just slam it as hard as you can either, unless you can do it and still maintain good control.