Does Ball Weight Effect Throw?

I knew it was coming

CJ Wiley said:
We played a lot with the Big Cue Ball, Metal Flake and "Mud Ball" back on the road. This is where I had such a big advantage using the 'Touch of Inside' (TOI)....it actually makes playing with the Big Ball much easier.....I used to "trap" players on a big table, using a Big Cue Ball.....this messes up big table players AND bar table players. :D
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I knew it wouldn't be long before toi would show up and yet again solve the worlds problems.
 
Andrew Manning said:
Shouldn't the size difference create another significant variable here, in that the CB and OB won't be colliding at the equator, and thus there will be a downward component to the impulse at contact? A larger CB, in addition to cutting the OB, will also trap the OB against the cloth to some extent. I would think this would result in greater pressure at the point of contact, and thus a greater frictional force given the same coefficient of friction. Am I wrong?
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You are correct about the downward component of force (which can make the CB and/or OB hop and result in slower OB motion), but this would not change the OB direction (i.e., the amount of throw). Interaction between the bottom of the OB and the cloth has nothing to do with throw. Although, having the CB contact the OB above the equator does change the effective cut angle of the shot, just as it does with jump shots where the CB hits the OB while airborn (and some people might perceive this as a throw effect, but it isn't). For more info and demonstrations of overcutting with an above-equator hit, see the jump-shot over-cut resource page.

Regards,
Dave
 
Andrew Manning said:
Shouldn't the size difference create another significant variable here, in that the CB and OB won't be colliding at the equator, and thus there will be a downward component to the impulse at contact? A larger CB, in addition to cutting the OB, will also trap the OB against the cloth to some extent. I would think this would result in greater pressure at the point of contact, and thus a greater frictional force given the same coefficient of friction. Am I wrong?
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Because the ball material is so stiff compared to the cloth, a downward CB-to-OB collision at a modest angle is really unaffected by the resulting OB-to-table collision. Per the ball-contact-time resource page, a ball-to-ball collision occurs in about 0.0003 seconds (300 microseconds). Per HSV B.44 - cloth compression and cue ball trajectory for draw shots of various elevations, an OB takes about 0.002 seconds to compress the cloth and rebound off the slate at an angle ... about 7-times longer than the ball-ball collision. Therefore, the CB-to-OB collision is mostly done before any significant force builds up between the OB and the cloth.

I hope that makes sense. You guys are making my head hurt making me think about this stuff. That's too much for a Friday. :grin:

Catch you later,
Dave
 
Andrew Manning said:
Shouldn't the size difference create another significant variable here, in that the CB and OB won't be colliding at the equator
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FYI, even though a larger CB will hit the OB above the equator, which increases the effective cut angle some (creating a thinner hit), the larger size of the CB causes a sooner hit, which decreases the effective cut angle some (creating a fuller hit). The 2nd effect is bigger than the first, creating a fuller hit than expected. I just convinced myself of this fact by drawing a top view of a half-ball hit with both an equal-size CB and a larger CB (along the same CTE line). The point of contact between the balls must lie on the line-of-centers between the balls. The line-of-centers for the larger ball creates a smaller cut angle and fuller hit (even with the above-equator hit effect). Draw it out yourself if you are still not sure.

Regards,
Dave
 
Don't pretend you don't love all of this, Dr Dave!!!

Thanks for the replies. I'm none the wiser but atleast I know mass alone doesn't affect throw so I'm smarter than I was yesterday.
 
TOI is patrolling the world and the internet 24 hours a day

J-Flo said:
I knew it wouldn't be long before toi would show up and yet again solve the worlds problems.
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Yes, there's an entire "TOI Task Force" patrolling the internet 24 hours a day. ;)


toi.jpg
 
dr_dave said:
Because the ball material is so stiff compared to the cloth, a downward CB-to-OB collision at a modest angle is really unaffected by the resulting OB-to-table collision. Per the ball-contact-time resource page, a ball-to-ball collision occurs in about 0.0003 seconds (300 microseconds). Per HSV B.44 - cloth compression and cue ball trajectory for draw shots of various elevations, an OB takes about 0.002 seconds to compress the cloth and rebound off the slate at an angle ... about 7-times longer than the ball-ball collision. Therefore, the CB-to-OB collision is mostly done before any significant force builds up between the OB and the cloth.

I hope that makes sense. You guys are making my head hurt making me think about this stuff. That's too much for a Friday. :grin:

Catch you later,
Dave
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But wait: if both balls hop up after contact, then during contact the CB must have been deflected upward.

Wouldn't that upward force imply a greater-than-normal amount of pressure during CB-OB contact, above and beyond the pressure that results in normal parallel-to-the-table-bed forces?

I'm imagining a boulder of a CB, with a diameter of several feet, "cutting" a marble. Seems like the marble would get trapped under the boulder and crushed. This "trapping" would have to do with the boulder squeezing downward on the marble from above with great pressure, increasing friction and stopping the marble from deflecting away. Wouldn't a small version of that effect come into play with a slight CB-OB size difference?

-Andrew
 
Andrew Manning said:
dr_dave said:
Because the ball material is so stiff compared to the cloth, a downward CB-to-OB collision at a modest angle is really unaffected by the resulting OB-to-table collision. Per the ball-contact-time resource page, a ball-to-ball collision occurs in about 0.0003 seconds (300 microseconds). Per HSV B.44 - cloth compression and cue ball trajectory for draw shots of various elevations, an OB takes about 0.002 seconds to compress the cloth and rebound off the slate at an angle ... about 7-times longer than the ball-ball collision. Therefore, the CB-to-OB collision is mostly done before any significant force builds up between the OB and the cloth.
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But wait: if both balls hop up after contact, then during contact the CB must have been deflected upward.
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That's correct.

Andrew Manning said:
Wouldn't that upward force imply a greater-than-normal amount of pressure during CB-OB contact above and beyond the pressure that results in normal parallel-to-the-table-bed forces?
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No, unless there is cling/skid/kick.

Andrew Manning said:
I'm imagining a boulder of a CB, with a diameter of several feet, "cutting" a marble. Seems like the marble would get trapped under the boulder and crushed. This "trapping" would have to do with the boulder squeezing downward on the marble from above with great pressure, increasing friction and stopping the marble from deflecting away. Wouldn't a small version of that effect come into play with a slight CB-OB size difference?
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The CB would "trap" the OB if it were many times larger than the OB (e.g., like the tip can "trap" the CB with a highly-elevated and poorly executed jump or masse shot); but with reasonable ball size differences, no trapping is occurring. The OB moves away from the CB freely as it compresses the cloth and bounces off the slate.

Regards,
Dave
 
Dave,

So, if you had a cue ball that had the mass of a ping pong ball, the throw would be the same as a regulation 6 ouncer?:confused:
 
Since he's now banned, I guess Pidge turned out to be The Thaiger after all.
 
desmocourtney said:
Dave,

So, if you had a cue ball that had the mass of a ping pong ball, the throw would be the same as a regulation 6 ouncer?:confused:
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Yes, assuming the lighter ball has the same frictional properties on the surface, and assuming the CB hits the OB with enough speed to actually move the OB.

Now, the amount of throw does vary with CB speed, and to create the same OB speed, a lighter CB would need to be given faster speed, and this would result in less friction and less throw. However, with reasonable differences in ball weights, this effect would not be significant.

Regards,
Dave
 
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