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The_Doctor
02-15-2006, 04:07 AM
Over in the UK we play a game called English 8 ball. It is played with very small balls, 2" object balls and a 1 7/8" cue ball.
I was wondering what effect throw may have on balls this small. Throw seems to be something that is not considered in snooker or English pool and is only something that I have become aware of since discovering the joys of American pool (or "pool" as Americans seem to call it).
I was thinking down the line of less mass therefore less momentum for a given velocity, therefore less force, therefore less friction and less throw. But then I was thinking less inertia for the throw to overcome.
That is as far as my physics understanding will take me so I wondered if anyone had any suggestions.
I assume that it still exists with the smaller balls but as no one over here seems to know about it I wondered if it has a noticeable effect.

Thanks, Andy.

(sorry I don't know the weight of the balls, I've tried to find it but it appears to be elusive)

Icon of Sin
02-15-2006, 05:44 AM
I imagine it would be harder to control the throw since there is much less ball, but I have never played that way.

BTW, English 8 ball, thats called Pub Pool right? I think the movie stickmen was based on it.

Bob_Jewett
02-15-2006, 11:08 AM
<blockquote><font class="small">Quote The_Doctor:</font><hr> ... I was wondering what effect throw may have on balls this small. Throw seems to be something that is not considered in snooker or English pool and is only something that I have become aware of since discovering the joys of American pool (or "pool" as Americans seem to call it).
... <hr /></blockquote>
I have seen some very good snooker players who seem to be unaware of both throw and transfered side.

The maximum angle of throw is determined by the coefficient of friction between the balls, and does not depend on either their size or density, as I understand it.

A complication (in all cases of throw) is that the coefficient of friction depends on the relative speed of the two surfaces, and it goes down for higher surface speeds. This means that more side does not necessarily result in more throw.

A further complication is that in the UK, many people use the word "throw" in a complete different sense. What we call "squirt" or "deflection" is what they call "throw."

Jal
02-15-2006, 11:50 AM
<blockquote><font class="small">Quote The_Doctor:</font><hr>...I was thinking down the line of less mass therefore less momentum for a given velocity, therefore less force, therefore less friction and less throw. But then I was thinking less inertia for the throw to overcome....<hr /></blockquote>I think you're on the right track. In general, smaller balls with less mass will throw the same as larger balls with more mass, given the same surface conditions. As you were leading toward, the force is less but the mass is also less and these differences cancel out. The induced spin, however, will be greater for the smaller balls.

If the cueball and object balls are mismatched in weight and size, I'm not sure. There are complications arising from the induced spin and how this affects the relative surface speed and thus the amount of friction between them. In the case where the relative surface speed is large compared to the changes to it that take place during the collision, the throw should be the same (or very nearly so) as with larger balls well matched in weight and size. It may be true that the throw is the same in all cases, but I haven't worked out the details.

Jim

dr_dave
02-15-2006, 11:51 AM
Bob's reply sums it up fairly well. If you want to see the technical details, refer to TP A.14 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-14.pdf). There are also some good conclusion summaries and comments under "throw" in the threads summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html).

Regards,
Dave

<blockquote><font class="small">Quote The_Doctor:</font><hr> Over in the UK we play a game called English 8 ball. It is played with very small balls, 2" object balls and a 1 7/8" cue ball.
I was wondering what effect throw may have on balls this small. Throw seems to be something that is not considered in snooker or English pool and is only something that I have become aware of since discovering the joys of American pool (or "pool" as Americans seem to call it).
I was thinking down the line of less mass therefore less momentum for a given velocity, therefore less force, therefore less friction and less throw. But then I was thinking less inertia for the throw to overcome.
That is as far as my physics understanding will take me so I wondered if anyone had any suggestions.
I assume that it still exists with the smaller balls but as no one over here seems to know about it I wondered if it has a noticeable effect.

Thanks, Andy.

(sorry I don't know the weight of the balls, I've tried to find it but it appears to be elusive) <hr /></blockquote>