To Bob Jewett
- Thread starter randyg
- Start date
cleary said:
They do "compact" (although I prefer the term "deform"), a little.
Randy, assuming the same CB speed in both cases, in a full hit there will be more pressure between the balls, and more deformation, and therefore a larger contact patch, than there would be in a cut shot.
The reason is that there's a larger transfer of momentum in the full hit; in the full hit the CB loses all its momentum, and the OB gains the maximum amount of momentum. In a cut shot, the CB retains much of its momentum, and the OB is given a smaller amount of it.
The larger transfer of momentum of the full hit requires the CB to exert a larger force (impulse) on the OB during contact in order to stop the CB and start the OB. More force means more deformation, means larger contact patch.
-Andrew
cleary said:
The balls do compact. That's why the surface area of contact is not zero. The area of contact should be smaller for a cut shot that a full shot for the same cueball speed.
This is because the contact surface size depends on the relative speed of the two balls along their line of centers. Essentially the contact area will follow the OBJECT ball speed. It will be larger whenever the object ball speed is larger.
randyg said:
No. The cue ball speed is the result of how hard the stick hit the ball.
The object ball speed is the result of how hard the balls hit each other. The size of the contact patch is also the result of how hard the balls hit each other. I guess that's probably the simplest plain-english way to describe it.
-Andrew
contact area importance?
There are some good answers already, but I am curious why you are asking the question. Do you think ball deformations are significant enough for us to consider? I'm not asking this to challenge you ... I'm just curious what you are thinking.
Thanks,
Dave
Randy,randyg said:
There are some good answers already, but I am curious why you are asking the question. Do you think ball deformations are significant enough for us to consider? I'm not asking this to challenge you ... I'm just curious what you are thinking.
Thanks,
Dave
dr_dave said:
I surely expected sombody to talk about vectors and such. lol.
ball compression instruction
OK. Here's my next question: Do you discuss ball compression when you teach? If so, in what context ... and why do you think it is important? Or, if a student asks if the balls compress much and if it affects shots, how do you respond?
Respectfully,
Dave
I respect your desire to continually learn and better understand things. I think constantly being "a student of the game" is an important attribute of a great instructor like yourself.randyg said:
OK. Here's my next question: Do you discuss ball compression when you teach? If so, in what context ... and why do you think it is important? Or, if a student asks if the balls compress much and if it affects shots, how do you respond?
Respectfully,
Dave
Dave,
This are just a few of the questions that could be asked in RandyG's pool school. I am sure that he would provide all the details you've asked for in this forum.
This are just a few of the questions that could be asked in RandyG's pool school. I am sure that he would provide all the details you've asked for in this forum.
free info
I've actually been to Randy's pool school. He invited me several years ago. I thought he and his fellow instructors did a great job, and I often recommend his school.
My questions are not meant to be disrespectful. I'm just curious what he thinks is important, and why.
Regards,
Dave
Good point. It's probably not fair to ask Randy to give away all of his secrets on a public forum for free.Tom In Cincy said:
I've actually been to Randy's pool school. He invited me several years ago. I thought he and his fellow instructors did a great job, and I often recommend his school.
My questions are not meant to be disrespectful. I'm just curious what he thinks is important, and why.
Regards,
Dave
SPF fan
EDITED: Jim, I just realized you were directing your response to "Tom In Cincy." Sorry for the confusion.
Regards,
Dave
I don't understand your point. I was just asking what Randy thought about ball compression and how he teaches this topic.
I am certainly not a spokesman for Randy or SPF; although, I am a fan and supporter. I think Randy has done a lot for the game.
Like everybody else, I am here to learn and contribute.
Regards,
Dave
EDITED: Jim, I just realized you were directing your response to "Tom In Cincy." Sorry for the confusion.
Regards,
Dave
Jim,av84fun said:
I don't understand your point. I was just asking what Randy thought about ball compression and how he teaches this topic.
I am certainly not a spokesman for Randy or SPF; although, I am a fan and supporter. I think Randy has done a lot for the game.
Like everybody else, I am here to learn and contribute.
Regards,
Dave
Last edited:
av84fun said:
I sure hope I have satisfied your questions to my post. Have a good day
cleary said:
Glad I could help.
-Andrew
randyg
Hi Randy,randyg said:
As others have pointed out, the contact patch is larger according to how much energy is transferred from ball to ball, so a thin hit will have a smaller patch than a full hit, and a harder shot will have a larger contact patch than a softer shot.
One thing to remember in this, that a lot of people seem to be confused by, is that the size of the contact patch has absolutely nothing to do with the aiming accuracy required on a particular shot. The patch width does not give any indication of how precisely the cue ball must hit the object ball to get it into the pocket. In the same way, the contact patch of the tip on the ball gives no indication of how accurate you must be in tip placement to achieve a particular precision of placement of the cue ball.
