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Ballistic Billiards
04-27-2008, 03:29 PM
The general consensus seems to be that the dwell time of the tip
on the ball is ~1ms (millisecond) or 1/1000 of a second.

This is interesting to me because, in golf, the dwell time is considerably
shorter at ~.5 ms. Yet in that ~.5 ms, while the club is in contact with
the ball, the club has moved the whole way through the ball.

Even in tennis, with a soft ball, the contact time is only ~5 ms.
Croquet, ~1 ms.
In croquet, tests have been done that show a variance in the
contact time upwards of 2ms.
The numbers that I saw were 1.5-3.7 ms. depending upon what type
of stroke was used.

Back to billiards.
Without doing the math, it seems that the tip is in contact with
the ball for the first few inches of the CB:OB journey.
Maybe someone wants to do the math, I don't.

the physics of croquet vs golf. Link (http://www.mauicroquetclub.org/coaching/analysis/ThePhysicsOfHittingACroquetBall.htm)

av84fun
04-27-2008, 04:37 PM
The general consensus seems to be that the dwell time of the tip
on the ball is ~1ms (millisecond) or 1/1000 of a second.

This is interesting to me because, in golf, the dwell time is considerably
shorter at ~.5 ms. Yet in that ~.5 ms, while the club is in contact with
the ball, the club has moved the whole way through the ball.

Even in tennis, with a soft ball, the contact time is only ~5 ms.

5X longer than a pool shot seems right to me.

Croquet, ~1 ms.
In croquet, tests have been done that show a variance in the
contact time upwards of 2ms.
The numbers that I saw were 1.5-3.7 ms. depending upon what type
of stroke was used.

Back to billiards.
Without doing the math, it seems that the tip is in contact with
the ball for the first few inches of the CB:OB journey.Maybe someone wants to do the math, I don't.

the physics of croquet vs golf. Link (http://www.mauicroquetclub.org/coaching/analysis/ThePhysicsOfHittingACroquetBall.htm)

Slow mo video shows that not to be true. Unlike golf, the pool cue slows down dramatically at CB contact so there is a dramatic differential between cue speed and CB speed after the millisecond (or whatever) of contact.

There are videos that show both the contact time and the reduction in cue speed that I think either/both Bob Jewett and Dr_Dave have posted.

Jim

Paul Dayton
04-27-2008, 04:42 PM
Predator did some very high speed filming and the cue does slow down and the ball is long gone. A milli second seems right.

td873
04-27-2008, 05:18 PM
The general consensus seems to be that the dwell time of the tip
on the ball is ~1ms (millisecond) or 1/1000 of a second.

Back to billiards.
Without doing the math, it seems that the tip is in contact with
the ball for the first few inches of the CB:OB journey.
Maybe someone wants to do the math, I don't.

I think the Jacksonville project illustrated the contact time in ultra-slow-mo. See here (http://www.sfbilliards.com/articles/1999-04.pdf). And I'm certain Dr. Dave has also illustrated this. Try: HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-77.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-78.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-79.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-80.htm)or HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-81.htm).

I believe your 1ms estimate is correct. I would bet the distance during contact is about 1/8" -1/4" or so. Maybe 1/2". But not much more than that.

Was there a question associated with this or just a statement in general?

Cheers,

-td

av84fun
04-27-2008, 07:02 PM
I think the Jacksonville project illustrated the contact time in ultra-slow-mo. See here (http://www.sfbilliards.com/articles/1999-04.pdf). And I'm certain Dr. Dave has also illustrated this. Try: HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-77.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-78.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-79.htm), HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-80.htm)or HERE (http://www.billiards.colostate.edu/high_speed_videos/new/HSVA-81.htm).

I believe your 1ms estimate is correct. I would bet the distance during contact is about 1/8" -1/4" or so. Maybe 1/2". But not much more than that.

Was there a question associated with this or just a statement in general?

Cheers,

-td

I'll bet on 1/4 in.

And your avatar really....ummmmm....BUGS me! (-:

TOO FUNNY! I went to squash it with my thumb...TWICE!! Thanks for the chuckle.

(-:

Ballistic Billiards
04-27-2008, 07:57 PM
This is what I thought was really interesting.
The contact time between mallet and ball is as short as .09ms,
and as long as 4.5ms.
coop, just looking for more input

Patrick Johnson
04-27-2008, 08:12 PM
Without doing the math, it seems that the tip is in contact with the ball for the first few inches of the CB:OB journey.

Here's a high speed video that shows it's only about 1/8 inch:

http://billiards.colostate.edu/high_speed_videos/new/HSVA-78.htm

pj
chgo

dr_dave
04-27-2008, 08:55 PM
FYI, cue tip contact time info can be found here:
For typical pool shots (1-10 mph) and typical contact times (about 0.001 sec), the tip is in contact with the CB for less than 1/4 inch.

Regards,
Dave

The general consensus seems to be that the dwell time of the tip
on the ball is ~1ms (millisecond) or 1/1000 of a second.

This is interesting to me because, in golf, the dwell time is considerably
shorter at ~.5 ms. Yet in that ~.5 ms, while the club is in contact with
the ball, the club has moved the whole way through the ball.

Even in tennis, with a soft ball, the contact time is only ~5 ms.
Croquet, ~1 ms.
In croquet, tests have been done that show a variance in the
contact time upwards of 2ms.
The numbers that I saw were 1.5-3.7 ms. depending upon what type
of stroke was used.

Back to billiards.
Without doing the math, it seems that the tip is in contact with
the ball for the first few inches of the CB:OB journey.
Maybe someone wants to do the math, I don't.

the physics of croquet vs golf. Link (http://www.mauicroquetclub.org/coaching/analysis/ThePhysicsOfHittingACroquetBall.htm)

Jal
04-27-2008, 11:32 PM
...For typical pool shots (1-10 mph) and typical contact times (about 0.001 sec), the tip is in contact with the CB for less than 1/4 inch.Dr. Dave,

I think Patrick is closest with his measurement of 1/8". In the case where the cueball comes off at only 1.3X stick speed because of compression losses (instead of 1.5X), I believe its time averaged speed during the collision would be about 1.15X its final speed divided by 2 (it would be 1X this in a perfectly elastic collision). So if its final speed is, say, 10 mph (=176.0 in/sec), and contact time is .001 sec, it should move about 1/10".

(I know it's a nitpick, but since people are trying to get it within some fraction of an inch....)

Jim

HollyWood
04-28-2008, 12:15 AM
With a no proporsity tip will it be more or less? thanks How about with the ob-1 shaft, stiff and a no-proporsity Kamuii II Hard. I think good topic and I should ask as well, with a Pred 314-2 or z-2, thats three more questions. thanks for any generated responces mark

dr_dave
04-28-2008, 09:00 AM
Dr. Dave,

I think Patrick is closest with his measurement of 1/8". In the case where the cueball comes off at only 1.3X stick speed because of compression losses (instead of 1.5X), I believe its time averaged speed during the collision would be about 1.15X its final speed divided by 2 (it would be 1X this in a perfectly elastic collision). So if its final speed is, say, 10 mph (=176.0 in/sec), and contact time is .001 sec, it should move about 1/10".

(I know it's a nitpick, but since people are trying to get it within some fraction of an inch....)

JimJim,

I wasn't trying to provide a specific answer for a specific shot because tip contact time and distance varies some with shot speed and tip hardness. I was just trying to reinforce that the contact distance is much smaller than some people think. I agree that typical contact distances will be much less than 1/4 inch.

Regards,
Dave

wjpjr
04-28-2008, 09:06 AM
Here's another slow speed vid of tip contact.
http://www.kamuitips.com/

Bob Jewett
04-28-2008, 09:07 AM
This is what I thought was really interesting.
The contact time between mallet and ball is as short as .09ms,
and as long as 4.5ms.
coop, just looking for more input
I think you have a decimal point off in the low case. For the high end of contact time, I suspect the players are using the equivalent of a push shot.

Patrick Johnson
04-28-2008, 09:27 AM
a no proporsity tip

Where do you get those?

pj
chgo

Ballistic Billiards
04-28-2008, 12:17 PM
The important factor that I see isn't the distance, it is the difference
in time of contact.

Bob,
The .09ms came from the link that I provided.
Here it is again.
http://www.oxfordcroquet.com/tech/hall/index.asp
You're right about the push but standard shots are up to 4ms.

-cOOp

mikepage
04-28-2008, 12:27 PM
The important factor that I see isn't the distance, it is the difference
in time of contact.

Bob,
The .09ms came from the link that I provided.
Here it is again.
http://www.oxfordcroquet.com/tech/hall/index.asp
You're right about the push but standard shots are up to 4ms.

-cOOp

And he's right about the 0.09 really being 0.9, imo. It's pretty clear from the tales of numbers in the link you provided.

av84fun
04-28-2008, 12:45 PM
Seems to me that the methodology of this test was highly flawed.

"For this purpose, a few strands of copper wire were wound around the ball. At right-angles to this, a strip of aluminium foil was fixed to the ball. Foil was also taped to the end faces of the mallet. The two metal surfaces were connected to an electronic timer so that when the surfaces were in contact the timer was operational."

Introducing copper wire and aluminum foil to the contact area absolutely altered the true dynamcis of the contact...the only issue being to what extent.

Super slo mo video of the actual surfaces contacting each other is a far more definitive approach IMHO.

Regards,
Jim

klockdoc
04-28-2008, 01:16 PM
Here's another slow speed vid of tip contact.
http://www.kamuitips.com/

Question..:confused:

Is the cue shaft rising up after contacting the CB in this video
1). result of the tip being hit towards the top of the CB, or,
2). a result of the shooter follow through?

cigardave
04-28-2008, 01:28 PM
Question..:confused:

Is the cue shaft rising up after contacting the CB in this video
1). result of the tip being hit towards the top of the CB, or,
2). a result of the shooter follow through?

I vote for #1... the upward motion of the cue is a result of Newton's Third Law of Motion... For every action there is an equal and opposite reaction.

The contact point of the cue with the ball is such that the bottom of the tip strikes the ball (due to the follow that's imparted on the cue ball)... and therefore the cue tends to rise up due to the vector of the contact force being up and to the left (relative to the cue's tip).

mikepage
04-28-2008, 01:30 PM
Question..:confused:

Is the cue shaft rising up after contacting the CB in this video
1). result of the tip being hit towards the top of the CB, or,
2). a result of the shooter follow through?

Definitely # 1

the tip on a whippy shaft might go up twice as far as one on a stiff shaft

Thunderball
04-28-2008, 01:35 PM
http://www.kamuitips.com/

Don't know who they got hitten balls in some of the vids,but there is some pretty dam sporty shots on that page.

Clicky on the pool table drawing to see the related vid.

av84fun
04-28-2008, 03:01 PM
Here's another slow speed vid of tip contact.
http://www.kamuitips.com/

Really fun link. But I am highly suspicious that in the demo shots that you click on the pool table diagrams to see, they are using a light CB.

Check out the 3rd one down from top center. I think that few players could get that much masse on a new, standard weight CB.

(-:

Bob Jewett
04-28-2008, 03:18 PM
... The .09ms came from the link that I provided.
...
Yes, I found it in the text, but it is a mistake. Someone typed 0.09 when they were supposed to type 0.9. There is no other contact time close to that time. The other possibility is that the equipment malfunctioned.

Shortside K
04-28-2008, 09:57 PM
The general consensus seems to be that the dwell time of the tip
on the ball is ~1ms (millisecond) or 1/1000 of a second.

This is interesting to me because, in golf, the dwell time is considerably
shorter at ~.5 ms. Yet in that ~.5 ms, while the club is in contact with
the ball, the club has moved the whole way through the ball.

Even in tennis, with a soft ball, the contact time is only ~5 ms.
Croquet, ~1 ms.
In croquet, tests have been done that show a variance in the
contact time upwards of 2ms.
The numbers that I saw were 1.5-3.7 ms. depending upon what type
of stroke was used.

Back to billiards.
Without doing the math, it seems that the tip is in contact with
the ball for the first few inches of the CB:OB journey.
Maybe someone wants to do the math, I don't.

the physics of croquet vs golf. Link (http://www.mauicroquetclub.org/coaching/analysis/ThePhysicsOfHittingACroquetBall.htm)