power vs. speed on the break
- Thread starter dave sutton
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The formula is in Bob Byrne's "Advanced Technique" book in the chapter that discusses break cue weights.asn130 said:
If the weights were equal, the stick would stop dead and the cue ball would leave with the speed of the stick. But suppose a freight train hit a sitting tennis ball. The train would not slow down at all. The tennis ball would not stick to the front of the train but would bounce forward and be going faster than the train. A detailed analysis says that if no energy is lost in the collision, the tennis ball would be moving at twice the initial (and final) speed of the train.
What happens in between is covered by the formula. There is an additional correction due to loss of energy in the cue tip.
If a stick is moving at 10MPH, the simple formula predicts a ball speed of 15MPH, but what has been measured with a normal tip is about 13MPH. During the collision, which takes a thousandth of a second, the stick will slow down to about 5MPH.
The key to the pool shot is that the tip is springy. At some point in the collision, the tip is at maximum compression, and that is exactly when the cue ball and cue stick are moving at the same speed. Then the tip starts to spring back, propelling the cue ball off the tip.
so whats the consensus. Heavier is better? my head hurts from readin all this technical stuff. I think i need a beer now. 
I think the consensus is that the best weight depends on the player. One observation is that some good players use lighter sticks to play with than to break with. My feeling is that 2 ounces one way or the other won't make as much difference as having a good breaking tip on your cue, which seems to mean as hard as possible.TXsouthpaw said:so whats the consensus. Heavier is better? my head hurts from readin all this technical stuff. I think i need a beer now.
I've always taken a basic guess at this question which is where is the point of negative return?
An example is that you can probably throw a baseball faster than a softball, but I doubt that you can throw a golf ball faster than a baseball. Another is something I saw on ESPN where they pitted a pitcher from Stanford and Team USA fast pitch softball player Jenny Finch in a time test (how long from pitchers mound to home plate).
The Stanford pitcher threw 90+ mph. Jenny Finch threw 70+ mph and busted the pressure plate into a million pieces.
I can see the same happening in a break. I can guarantee I can put up a much more powerful break with a 20oz cue against a 17oz cue.
An example is that you can probably throw a baseball faster than a softball, but I doubt that you can throw a golf ball faster than a baseball. Another is something I saw on ESPN where they pitted a pitcher from Stanford and Team USA fast pitch softball player Jenny Finch in a time test (how long from pitchers mound to home plate).
The Stanford pitcher threw 90+ mph. Jenny Finch threw 70+ mph and busted the pressure plate into a million pieces.
I can see the same happening in a break. I can guarantee I can put up a much more powerful break with a 20oz cue against a 17oz cue.
That reminds me of a story I heard on the derivation of the pound (lb).gunzby said:
A pound was approximately the perfect weight for a throwing rock. Lighter and it had too high a wind resistance ratio, heavier and it couldn't be tossed with high enough velocity. So the soldiers used to load up on pound sized rocks to throw at the enemy.
In your part about the 70mph throw busting the pressure plate, are you insunuating that one can throw slower with more power/energy in the ball (which ain't possible), or that she was more accurate?
Colin
Colin Colenso said:
She was throwing a heavier softball at 70+ mph while he was throwing 90+ mph with a lighter baseball. Both were accurate (the pressure plate was about half strikezone size), but she had much more power considering that she was throwing something heavier (even though it was softer) at a lower velocity than he was which was a lighter weight, harder surface and higher velocity.
She absolutely crushed that pressure plate. On a side note Jenny Finch is absolutely gorgeous.
Bob Jewett said:
In your train example the contact point of the tennis ball is elastic and the contact point of the train would be much less elastic( I think), however the tennis ball rebounds very fast. Is there a rebound speed relationship between the hardness or elasticity of both contact points? It seems to me that if a golf ball was substituted for the cue ball, the golf ball would rebound at a much higher speed than the cue ball.
The reason I ask that question leads to this question: will a tip which is very elastic (and hard
?) add speed to the cue ball?
By the way, your comments are respected and appreciated by the members of this forum.
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Tennesseejoe said:
A golf ball would rebound incredibly more than a cue ball because a golf ball is actually very elastic. When it is hit with a driver a golf ball actually flattens down to about 3/4 it's size.
A very hard tip will add speed because a leather tip is not elastic. In other words when you hit the cue ball with the tip it doesn't compress and spring forward to the point of making a significant impact on speed.
Oops. Typing too fast and not proofreading enough. I meant to say that the other way around. Some players change to a lighter stick to break.Bob Jewett said:
"Elastic" is a technical term in physics which basically means "has collisions without losing energy." I think the common notion of "elastic" is something like "rubbery." A steel ball bouncing off a steel plate is "elastic" and so is a super ball bouncing off nearly anything. A ball of clay is "inelastic" in that it will bounce hardly at all, with all the energy going into deforming the clay.Tennesseejoe said:
In general elasticity is independent of speed until you get up to a speed at which things start to break (deform permanently). A steel ball dropped onto an aluminum plate from an inch or so will bounce. From 100 feet, it might smush into the aluminum. At that point, all bets are off.
Somewhere in between perfect elasticity and zero bounce is something like the standard leather tip. It has some bounce, but it also absorbs energy on each shot, like maybe 20%. It seems to be able to absorb the energy without changing much for a long time. For a break cue, you would like a tip that absorbs much less energy, like the hard leather or phenolic tips people are using. It's not clear that they have to be hard -- I tried a tip made from a super ball, but it fractured and tore with just a little use, so I never got to test its efficiency..
In the case of substituting a golf ball for a cue ball, the golf ball is still limited to less than twice the speed of the stick, even if it is perfectly elastic.
Agreed, and I've got you now on the heavier softball having more momentum, or keeping more.gunzby said:
And you're right about Jenny Finch as a google image search confirmed *drools*
Colin