Quick question about Cut Induced Throw

A

Amaury

Member
Hello,

when you cut a ball (for example 45 degrees) , does the object ball goes straight with an initial angle less than 90°, or does it start on the tangent line THEN does a slight curve?
I am asking because every time I pot a ball while compensating for throw, I first think I missed it and then the OB finally goes in. Just tell me if my eyes are wrong.

Thanks
 
Solution
Bob Jewett
straightline said:
Any time the separation deviates from the line of centers, something somewhere, curves.
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And if Fat Fred is standing on the right side of the table, he will help the ball curve around an obstruction. Gravity rules!

The question is whether the curve is significant on any normal shot. It is not. The OP should worry about it no more than he should worry about where Fat Fred is standing. Unless the floor really needs bracing.
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straightline said:
Here. Wasn't hard to find.

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Ah... OK.

Though clever as sort of a proof of concept, what Dave does is essentially a gaff shot --purposely inducing skid. In the original post here, the guy is asking if he's seeing the object ball curve on a normal cut shot with a normal amount of throw. He isn't.

To make an analogy, someone might ask, "Am I seeing the football on a field goal apparently curve to the right in the northern hemisphere due to rotation of the earth?" And the answer is no, you're not perceiving that. Then Dr Dave might build a robot that kicks a field goal a quarter mile, aim a thousand kicks at the left goal post, and show that a high percentage of them bounce in.
 
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mikepage said:
Ah... OK.

Though clever as sort of a proof of concept, what Dave does is essentially a gaff shot --purposely inducing skid. In the original post here, the guy is asking if he's seeing the object ball curve on a normal cut shot with a normal amount of throw. He isn't.

To make an analogy, someone might ask, "Am I seeing the football on a field goal apparently curve to the right in the northern hemisphere due to rotation of the earth?" And the answer is no, you're not perceiving that. Then Dr Dave might build a robot that kicks a field goal a quarter mile, aim a thousand kicks at the left goal post, and show that a high percentage of them bounce in.
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You'll have to ask him what he thinks. Common sense tells me the ball has to get <around> a hook.
 
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mikepage said:
In the original post here, the guy is asking if he's seeing the object ball curve on a normal cut shot with a normal amount of throw. He isn't.
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Exactly.
But thanks to straighline link, it's maybe possible that my balls are WAY too dirty (it's very plausible, as the table also is).
Now I think it probably just the table that isn't level as I think.
 
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straightline said:
Any time the separation deviates from the line of centers, something somewhere, curves.
Click to expand...
And if Fat Fred is standing on the right side of the table, he will help the ball curve around an obstruction. Gravity rules!

The question is whether the curve is significant on any normal shot. It is not. The OP should worry about it no more than he should worry about where Fat Fred is standing. Unless the floor really needs bracing.
 
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Solution
There's no curve involved. CIT (cut induced throw) is just a result of friction.

Think of friction like glue. Imagine you took the cue ball and object ball and completely covered them in the strongest glue you could find. Now play an extremely slow shot. When the balls impact with each other they will stick together and the entire mass (two balls connected) will slide forward from the cue ball's momentum before stopping, permanently stuck together.

Now let's play the shot a little faster. Still very slow, but just fast enough so the balls can't permanently stay glued together. At impact, the two balls glue together again and the entire mass slides forward for a short distance and then the balls release and go their separate ways.

This is exactly what CIT throw is doing. The object ball is still releasing at that same 45 degree angle toward the pocket but friction is causing the balls to glue together momentarily and shift forward before releasing which causes the object ball to miss the center of the pocket.
 
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FeelDaShot said:
…the two balls glue together again and the entire mass slides forward for a short distance and then the balls release…
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FeelDaShot said:
…The object ball is still releasing at that same 45 degree angle toward the pocket
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No, throw changes the angle the object ball travels, and it happens more or less immediately - there’s no “sliding forward” together to speak of.

pj
chgo
 
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Bob Jewett said:
And if Fat Fred is standing on the right side of the table, he will help the ball curve around an obstruction. Gravity rules!

The question is whether the curve is significant on any normal shot. It is not. The OP should worry about it no more than he should worry about where Fat Fred is standing. Unless the floor really needs bracing.
Click to expand...
We don't get to play in laboratories. In most non upscale venues, throw is a meaningful curvature of the line of centers - how Dr. Dave could clear those hooks - extra chalk and all...
 
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Patrick Johnson said:
A meaningful deviation from the line of centers, but with no curvature ordinarily.

I know… nitpicky. It’s what I do.

pj
chgo
Click to expand...
U is U

Bob Jewett said:
No, it isn't. You have misunderstood the situation. There is no significant curve on throw shots under normal conditions.
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But lemme address this non issue directly. Balls can skid under possibly all but the most pristine, lubed, conditions. That in and of itself is meaningful but here's the point: you can clear the edge of an obstruction with skid. A ball within skidding distance of the pocket and limited to an arbitrary 'less than half' of the near (to the shooter) side of the pocket by a very close ball, can be skidded past the obstruction and into the pocket - often center or more pocket. You may lack the precision to rely on a cut like this but they do come up. You can use this to your advantage by playing those cuts from the skid side ie the big side. I know both of you are 1 hole practitioners. Meaningful.
 
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straightline said:
Dr. Dave showed that CIT can curve an object ball. So that.
It's all low speed/high friction stuff.
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It kind of proves that speed is important and Island Drive’s observation about hitting the OB contact point differently with faster speed wasn’t mentioned or illustrated by Dr. Dave. In fact, the shots demonstrated required slow speed.
 
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Also, at a slow speed, the transfer causing the object ball to dramatically change direction upon contact....shooter must apply a horizontal spinning cue ball.... struck at 9 or 3 o'clock.
 
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straightline said:
U is U


But lemme address this non issue directly. Balls can skid under possibly all but the most pristine, lubed, conditions. That in and of itself is meaningful but here's the point: you can clear the edge of an obstruction with skid. A ball within skidding distance of the pocket and limited to an arbitrary 'less than half' of the near (to the shooter) side of the pocket by a very close ball, can be skidded past the obstruction and into the pocket - often center or more pocket. You may lack the precision to rely on a cut like this but they do come up. You can use this to your advantage by playing those cuts from the skid side ie the big side. I know both of you are 1 hole practitioners. Meaningful.
Click to expand...
Skid isn’t curve.

pj
chgo
 
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Patrick Johnson said:
Skid isn’t curve.

pj
chgo
Click to expand...
Here's some real wacko stuff you can debunk. You know how electricity - I forget if it's the current or the voltage, travels outside the wire? Probably current come to think of it. Anyway what if the actual energy of a pool ball collision exists outside of the balls and continues to influence their paths until they've stopped?
 
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Patrick Johnson said:
That doesn't say why it "has to curve". Skid throws the object ball in a straight direction (angled from the line of centers) - only masse spin (about the horizontal axis) can make it curve. What force creates masse spin on the object ball?

pj
chgo
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The line of centers passes energy which way? And then the ball ignores that entirely by heading off another way - um defying physics?
 
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