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View Full Version : Why does the CB hop on a power break?

dr_dave
07-08-2005, 01:19 PM
FYI, I received the following question via e-mail. I thought I would share it along with my answer to see if you guys have other viewpoints or insights.
<blockquote><font class="small">Quote e-mail question to Dr. Dave from a reader:</font><hr>
Have you used you high speed video equipment to demonstrate the following:

The only way the cue ball can come off the table on the break ( i.e.. 9-ball or 8-ball games) is if the cue ball is in the air before contacting a ball in the rack. The center of the cue ball must be above the center of the object ball it hits for the cue ball to make an upward motion.

I only bring this up because I believe that 99% of the pool population thinks that they are hitting the cue ball so hard it is "climbing" up and over the first ball contacted. IMPOSSIBLE. The only way this could happen is if they are using a larger diameter cue ball than the object ball. When the cue ball flies up or off the table, the breaker has slightly "hopped" the cue ball down the table and it is bounced into the rack, not rolled.

Thanks for any input or comments.<hr /></blockquote>

The only footage I have is HSV A.3, A.4, and A.22 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/index.html). I agree with you that a significant hop can occur only if the cue ball is slightly airborne at impact (assuming the balls are the same size). This is actually very common because the cue stick, which needs to be elevated over the rails, strikes down on the CB causing it to bounce. Although, it is possible for the CB to slide perfectly without bounce if the CB is hit slightly below center, resulting in vertical "squirt" that can cancel the elevated-cue jump effect.

As far as CB climbing is concerned, it is theoretically possible as a result of the vertical friction between the balls caused by topspin, but I have not observed it with high-speed video. Also, a good power break has only slight follow, probably not enough to cause significant hop due to "climbing" alone. However, even just slight follow is enough to make the CB bounce and skip on the way to the rack.

Dave

DickLeonard
07-10-2005, 09:57 AM
Dave I was going to bet a room owner \$1000 than making customers break off a cloth was like teeing up the cueball and the first foot or so the cueball was going to be launched. He decided not to take the bet,I was going to baby powder the table,then have a power breaker hit one,the powder would not have a track for at least one foot.

The room owner was throwing customers out for jumping balls off the table, when the real culprit was the room owner making them break off a cloth. I told him make them break off a dollar bill,you can't hurt the bill and it won't launch the cueball.####