sets plants and ball squeezing

[cocked hat]

Here's a question for the boffins,Who knows how far apart two balls can be before the 'squeeze' effect no longer applies?

When two balls are touching,as we all know,if the first is struck,say,on the left,the further ball runs off to the right.Why is that?Logic says that it should run straight ahead or if it veers off at all it ought to be to the left.Most explanations that I have heard dismiss this'as the squeeze effect'.

I don't understand how that could work.To further complicate matters,I've noticed that the same thing happens if the two balls are not quite touching,if the middle one (usually a red) is being squeezed then how can this happen?
I have occasionally had this happen to me when I was convinced that the normal rules of physics would apply,say,about 8mm.Does anyone know the maximum distance?

This effect doesn't seem to be affected by the pace of the shot,or to any great amount by spin.

For those who haven't tried this yet,it's worth practicing,a useful shot in any ones arsenal.

[Gimme Danger]

I wish I was sober, I would understand that then! I know it's something to do with plants, but can't work it out!

Should really stop on the whiskey and stella.

[checkSide]

I wish I was sober, I would understand that then! I know it's something to do with plants, but can't work it out!

Should really stop on the whiskey and stella.

Haha. That's a dangerous combo!

I drink stella and dark rum, that's bad enough! lol

[Robert602]

Physically it's a combination of two effects I'm sure you're familiar with.

If you put left hand side on a shot the cueball will 'grip' the object ball at the point of contact, and as its spinning it will throw the object ball slightly to the right.

Secondly, you'll know that when playing a back double you always need to slightly overcut, more so with half or quarter ball contacts than three quarter ball (so the phenomenon can't be blamed entirely on the squaring up effect of the cushion). That's basically because the action of the cueball 'side-swiping' the object ball sets the object ball spinning, with check side in this case.

Of course the same effects apply to all shots, you just don't normally care about the spin on the object ball. In a reverse plant you play to hit the first red at an angle (say on the left side), that sets it turning (with left hand side), which in turn throws the red it's close to (to the right). Because they're so close together the direction the first red starts travelling in makes little difference to the point of contact with the second red. On the other hand the further the first red has to travel, the more the side dissipates and the more its direction has an effect on the contact angle with the second red - it becomes a 'normal' plant.

So that's roughly the physics of the situation as I understand it. There are a lot of factors, and it's impossible to draw a neat dividing line between normal and reverse plants. The spins are all dictated by the initial 'side-swiping' action of the white, so a significant factor that isn't often thought about is the cueball's starting position. It's quite possible that a reverse plant that can be made from one position can't be made from another - even if you can see the same contact point. The type and condition of the balls make quite a bit of difference too.

So after all that I can't really answer you . 8mm does sound like quite a big gap but in certain conditions I suppose it's possible. On average I'd only expect an overriding reverse effect up to around half that.

[cocked hat]

Hi Robert,yes I can't disagree with anything that you say.The only thing is,if you play the cue ball with a lot of spin, it doesn't appear to alter the outcome.Also,if the imparted side throws the object ball,why doesn't the ball get thrown further if the balls are struck hard leaving less time for the spin to dissipate.
The other aspect is that of the distance the balls are apart,this distance would be greater if you hit the balls hard leading to the reverse effect continuing for some inches if you really gave it a cogwinder.This doesn't happen.
I've not yet played with the latest balls,I should be interested if they react the same.Regards,Tony.

[davis_greatest]

Also,if the imparted side throws the object ball,why doesn't the ball get thrown further if the balls are struck hard leaving less time for the spin to dissipate...

... because striking the ball harder reduces the time that the balls remain in contact, and thus reduces the imparting of secondary spin from one ball to another.

[Robert602]

That's my understanding too. It does seem a bit strange that playing with side on the cueball makes little or no difference though - I can only think that its effect is dwarfed by the side imparted by the glancing impact, but that does seem unintuitive to me. I'll give it a go with some spotted reds when I get a chance, and see if I can fathom what's going on.