The size of tidal bulges caused by movement of the oceans is maybe 50 feet maximum, a tiny amount in comparison with the polar vs. equatorial diameter difference of 26 miles. It doesn't affect the comparison of Earth with a billiard ball to any meaningful degree.
I did some higher-magnification images, but they weren't as interesting and didn't come out as well.
Unfortunately, that would not work very well. Sorry.
Yes.
It was an Aramith Pro Cup ("red measles") cue ball.
I wasn't surprised because pool balls are polished at the end of the manufacturing process. Polishing is an abrasive process, creating scratches ... even for smooth surfaces (albeit less deep scratches for shinier surfaces).
I don't think the scale of the scratches and blemishes is significant enough to affect throw very much unless the ball surface is damaged (e.g., scuffed, pitted, cracked, etc.) from long-term and/or abusive use.
I have imaged a large variety of ball conditions, but you will need to wait for my BD article to see and read about them. I'll try to remember to post a link in this thread when the article is available. I probably won't write it for several months, after I finish up my current series of articles.
You're very welcome.
So from Dr. Dave's picture we see a difference in heights of 1 micron (peak to valley) for spots that are within 1000 microns (1mm) of each other. Since the radius of a pool ball is about 28560 microns, the "local" roughness observed is about 1/30000 or about roughly 30 parts per million.
I did some higher-magnification images, but they weren't as interesting and didn't come out as well.
Unfortunately, that would not work very well. Sorry.
Yes.
It was an Aramith Pro Cup ("red measles") cue ball.
I wasn't surprised because pool balls are polished at the end of the manufacturing process. Polishing is an abrasive process, creating scratches ... even for smooth surfaces (albeit less deep scratches for shinier surfaces).
I don't think the scale of the scratches and blemishes is significant enough to affect throw very much unless the ball surface is damaged (e.g., scuffed, pitted, cracked, etc.) from long-term and/or abusive use.
I have imaged a large variety of ball conditions, but you will need to wait for my BD article to see and read about them. I'll try to remember to post a link in this thread when the article is available. I probably won't write it for several months, after I finish up my current series of articles.
You're very welcome.
For people who don't like clicking on links, here are the photos from the resource page:
For additional info, see the magnified ball surface resource page.
Regards,
Dave
Excellent post Bob (as usual)!
Sorry, but the pictures tell a different story.
Throw and spin transfer are caused by friction (static and/or sliding) between the balls. If the balls were manufactured with a rougher surface (i.e., higher peaks and valleys), there would be more friction and therefore more throw and spin transfer in some cases (but not all). Luckily, most pool balls have very similar and uniform surface properties so the frictional properties don't vary much (unless conditions are clingy due to old, beat up, chalk-smudged, and/or dirty balls).
As Bob has pointed out, the scratches are tiny. Undamaged and clean balls should react very uniformly at different contact points. This fact is clear from experiments people have performed (e.g., with throw).
I love pool even without all of the physics stuff; but with the physics stuff, I love it even more.
