Ball never touches bottom of pocket
- Thread starter nataddrho
- Start date
So, make the pocket lining slick and the balls won't spin back out, right?
I’ll take your word for it because it’s happened to me more than once. I even seen balls pop out in pro matches.
I think the analysis has nothing to do with a gyroscope. A uniform ball does not have an apparent axis, so there is no gyroscopic phenomenon. The axis changes when torque is applied to any place on the surface.
Some people try to invoke gyroscopes when talking about pool balls, but they don't apply there, either.
Some people try to invoke gyroscopes when talking about pool balls, but they don't apply there, either.
it may not have to do with gyroscopes, but it definitely has to do with angular momentum.
I believe that you are mistaken, amigo. There must be a gyroscopic effect due to conservation of angular momentum.
As bbb says, imho icbw. (But I don't think so...maybe you need to review freshman college mechanics. It's not easy stuff, but you're a smart guy.)
L.S. Dennis
Well-known member
Where's Dr. Dave?
There is no fixed (major) axis. The torques around each of the three axes of a uniform sphere can simply be integrated to find the current angular momentum around each of the axes and the axis of rotation. Angular momentum is conserved, but there is nothing going on like a gyroscope has.
Scientific term: trippy.
What are the three axes of a uniform sphere?...are there some canonical triple axes of a uniform sphere, or are you just talking about the Cartesian coordinate system? Either you're being fussy, or obtuse.
The sum of all the components of the angular momentum lies on a single axis, and this is what is conserved...legitimately referred to as a gyroscopic effect by the guy in the video, since gyroscopes illustrate this nicely, and he is aiming at an intuitive explanation.
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US pool players, have All the Answers even when we're wrong. 
I call it the ''loop de loo''.
bm
I call it the ''loop de loo''.
bm
DaWizard
Well-known member
The very rare occasion it happened to me I called it the "WADDAFAAAAAA"US pool players, have All the Answers even when we're wrong.
I call it the ''loop de loo''.
bm
In the video he is referring to the orbital period which is present in precession equations. Not an actual gyroscope.
DeeDeeCues
Well-known member
A gyroscope is a device. Gyroscopic effect is observed in any rotating body.
That's a cool physics demonstration, but I don't think that's the right effect in the pool ball situation. Invariably when I see this happen the object ball pops straight back out opposite the direction it went in, not flying out sideways like the ball in the video. It seems like it hits the lip of the pocket and goes straight down with enough force to bounce off the bottom of the pocket or another pocketed ball and, with the right spin, it comes back out. In fact, it usually hits the lip of the pocket again on the way out, causing it to bounce onto the table. I've never seen the object ball bounce out of the pocket off the table.
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Exactly!
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In the case of a pool ball, what is the observation that best illustrates gyroscopic effect?
DeeDeeCues
Well-known member
A really easy one is that a ball with side spin resists rolling longer than a center hit.
But we aren't talking about a normal cueball behavior, rather something that sometimes happens under specific conditions that is likely highly influenced by gyroscopic effect.
Is the analysis correct? I don't know, don't care. But, unless you are a flat-earther, you live on a spherish object that is highly affected by gyroscopic phenomenon. Admittedly, with some of your answers I often wonder whether you live on the same planet I do. I know that sounds like an insult, but it isn't intended to be.