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Mr. Bond
08-09-2017, 10:14 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

Cornerman
08-09-2017, 10:35 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

{edit: ~100 mph (NOT 60 mph per my previous} by my rough calculations (cheat sheet).

Black-Balled
08-09-2017, 10:39 AM
Www.calctool.org/calc/eng/aerospace/terminal

Good luck!

iusedtoberich
08-09-2017, 10:39 AM
Wait what am I forgetting from physics class? Isn't the wind resistance what causes the terminal velocity?

Black-Balled
08-09-2017, 10:40 AM
Wait what am I forgetting from physics class? Isn't the wind resistance what causes the terminal velocity?

Prob means no additionla reisstance...ie static conditions.

Linwood
08-09-2017, 10:46 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

Your question does not really make sense.

Terminal velocity is usually defined as the velocity in air, how fast is the fastest it will continue to fall.

The velocity of an object falling toward earth from "very far" with no air, assuming they both start with zero relative velocity, and ignoring effects of orbit and other planets, is about 11.2km/s. That is also the velocity (ignoring air) that you need going up to not come back down.

In theory (ignoring air) the distance to reach escape velocity falling is infinite, in practice you get pretty close within a few thousand, or hundreds of thousands of miles, depending on your definition of "close".

Now terminal velocity as normally defined (falling in air, how fast and how long to reach a steady speed) is a more interesting question, and I no longer remember enough math to figure it out. And of course it might vary by whether it was clean, or had some chalk left on it. :rolleyes:

But I think it's fair to say that the zero-air speed is a bit faster than anyone can break. Most regular, fairly dense objects' terminal velocity tends to be in the 80-200 mph range (one estimate I saw for a baseball is 95mph), so I would think a pool ball might be comparable.

I found a very old article saying a break shot is under 30mph, so I think they are slower than air-slowed terminal velocity as well. Article here (http://www.sfbilliards.com/Misc/onoda_all_txt.pdf). I can't vouch for its accuracy, google gave it to me.

Don Owen
08-09-2017, 10:49 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)
If I'm not mistaken, terminal velocity is the velocity when air resistance equals weight. Therefore, if there is no air resistance then "terminal velocity" looses its meaning or perhaps it's equal to escape velocity, around 25000 mph.

Ghosst
08-09-2017, 10:50 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

Terminal Velocity Calculator (http://www.wikihow.com/Calculate-Terminal-Velocity)

Gravitational Acceleration: 32ft/sec/sec

mchnhed
08-09-2017, 11:07 AM
No wonder I'm such a bad player......
I don't know any of this Pool Stuff!

Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)
And how many feet would it take to reach it?
And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)
~ 60 mph by my rough calculations (cheat sheet).

If I'm not mistaken, terminal velocity is the velocity when air resistance equals weight. Therefore, if there is no air resistance then "terminal velocity" looses its meaning or perhaps it's equal to escape velocity, around 25000 mph.

Terminal Velocity Calculator (http://www.wikihow.com/Calculate-Terminal-Velocity)
Gravitational Acceleration: 32ft/sec/sec

BC21
08-09-2017, 11:12 AM
Using the terminal velocity equation below, and assuming a normal air density of 1.27kg/m3, and a drag coefficient of 0.5 for a sphere.....

V = √(2mg/pAc)

m = mass of CB = 170.1g
g = gravity = 9.8m/s2
c = drag coefficient = 0.5
A = area of falling object = 25.66cm2 (convert to meters = 0.002566m2)
p = air density = 1.27kg/m3 (covert to grams3 = 1,270g/m3)

Plug it all in and get 45.24m/s, or 101.2mph. Nobody can break the balls that fast!

Cornerman
08-09-2017, 11:52 AM
Using the terminal velocity equation below, and assuming a normal air density of 1.27kg/m3, and a drag coefficient of 0.5 for a sphere.....

V = √(2mg/pAc)

m = mass of CB = 170.1g
g = gravity = 9.8m/s2
c = drag coefficient = 0.5
A = area of falling object = 25.66cm2 (convert to meters = 0.002566m2)
p = air density = 1.27kg/m3 (covert to grams3 = 1,270g/m3)

Plug it all in and get 45.24m/s, or 101.2mph. Nobody can break the balls that fast!
This is correct.

EtDM
08-09-2017, 12:03 PM
Using the terminal velocity equation below, and assuming a normal air density of 1.27kg/m3, and a drag coefficient of 0.5 for a sphere.....

V = √(2mg/pAc)

m = mass of CB = 170.1g
g = gravity = 9.8m/s2
c = drag coefficient = 0.5
A = area of falling object = 25.66cm2 (convert to meters = 0.002566m2)
p = air density = 1.27kg/m3 (covert to grams3 = 1,270g/m3)

Plug it all in and get 45.24m/s, or 101.2mph. Nobody can break the balls that fast!

I got results that were pretty close, but I used a drag coefficient of .1 for a smooth sphere, as found here:

https://en.wikipedia.org/wiki/Drag_coefficient

I think it's also important to note that due to his proclivity for historical info, Mr. Bond might also be interested in the terminal velocity of a carom ball. It seems the difference in diameter would actually up this figure a bit.

8ballr
08-09-2017, 12:05 PM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

Terminal velocity for falling objects is about 9.8 m/s squared...whether a marble, a piano or banana.
http://indianapublicmedia.org/amomentofscience/ground-golf-bowling-ball/

When you break, you are not limited by terminal velocity...superman could break the balls at 100x terminal velocity...but the cue ball would explode. :)

Agent 99
08-09-2017, 12:12 PM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

For me, the moment my opponent picks up the cue ball and throws it in my direction things become terminal .. :yikes:

Linwood
08-09-2017, 12:13 PM
Terminal velocity for all objects is about 9.8 m/s squared...whether a billiard ball or a cannon ball.

9.8 m/s^2 is the earth's gravity acceleration at the surface, it's not a velocity at all, much less a terminal velocity.

Cornerman
08-09-2017, 01:04 PM
Terminal velocity for falling objects is about 9.8 m/s squared...whether a marble, a piano or banana.
http://indianapublicmedia.org/amomentofscience/ground-golf-bowling-ball/

When you break, you are not limited by terminal velocity...superman could break the balls at 100x terminal velocity...but the cue ball would explode. :)

Ummmm... no.

mchnhed
08-09-2017, 01:23 PM
Ummmm... no.

Superman could break the balls at 100x terminal velocity...but the cue ball would explode. :)
Ahh..... the cue would shatter?

8ballr
08-09-2017, 03:24 PM
Ummmm... no.

9.8 m/s^2 is the earth's gravity acceleration at the surface, it's not a velocity at all, much less a terminal velocity.

Acceleration to a to terminal velocity...which for a cueball or a marble or just about any object in a free-fall position is about 195 km/h.

Cornerman
08-09-2017, 04:40 PM
Acceleration to a to terminal velocity...which for a cueball or a marble or just about any object in a free-fall position is about 195 km/h.

Still, no. Terminal velocity is mass and shape dependent. And air drag dependent. We're not talking about vacuums.

8ballr
08-09-2017, 04:44 PM
Still, no. Terminal velocity is mass and shape dependent. And air drag dependent. We're not talking about vacuums.

It has minimal affect...a golf ball will hit the ground at the same time as a watermelon. In a vacuum a hammer and a feather will fall at the same rate.

http://indianapublicmedia.org/amomentofscience/ground-golf-bowling-ball/

https://www.angio.net/personal/climb/speed.html

Cornerman
08-09-2017, 05:07 PM
It has minimal affect...a golf ball will hit the ground at the same time as a watermelon. In a vacuum a hammer and a feather will fall at the same rate.

http://indianapublicmedia.org/amomentofscience/ground-golf-bowling-ball/

https://www.angio.net/personal/climb/speed.html

You're not understanding. Terminal velocity is a very well understood physical thing. You're only talking about freefall in a vacuum.

pt109
08-09-2017, 05:41 PM
Terminal velocity for falling objects is about 9.8 m/s squared...whether a marble, a piano or banana.
http://indianapublicmedia.org/amomentofscience/ground-golf-bowling-ball/

When you break, you are not limited by terminal velocity...superman could break the balls at 100x terminal velocity...but the cue ball would explode. :)

It might depend on the mixture...

466956

8ballr
08-09-2017, 06:59 PM
You're not understanding. Terminal velocity is a very well understood physical thing. You're only talking about freefall in a vacuum.

You're confused...nobody is talking about a vacuum here...only you. Terminal velocity is the same for most all falling objects of any mass...ie if you drop a golf ball and a bowling ball from a building they will hit the ground at the same time. The exception is if you drop a feather and a bowling ball...obviously the bowling ball will first...unless in a vacuum then they will hit at the same time...ie on the moon.

Cornerman
08-09-2017, 07:24 PM
You're confused...nobody is talking about a vacuum here...only you. Terminal velocity is the same for most all falling objects of any mass...ie if you drop a golf ball and a bowling ball from a building they will hit the ground at the same time. The exception is if you drop a feather and a bowling ball...obviously the bowling ball will first...unless in a vacuum then they will hit at the same time...ie on the moon.

Youre confused. Sorry you don't understand. Terminal velocity has a specific meaning. Maybe you need to stay out of the discussion. Just a suggestion.

Terminal velocity is the maximum and constant final speed a falling object can obtain. The value is dependent on the shape of the object, its mass, and the density of the medium it fall through. Assuming the OP was talking about earth air, and normal pool balls, the terminal velocity is about 100 mph as calculated previously. A bowling ball, due to its high mass will have a higher terminal velocity (300mph or so).

Or you can tell me I'm confused. But I'm not. I'm just a mechanical engineer.

spktur
08-09-2017, 07:29 PM
The true terminal velocity is dead still as it hit the ground and was terminated.

8ballr
08-09-2017, 07:31 PM
Youre confused. Sorry you don't understand. Terminal velocity has a specific meaning. Maybe you need to stay out of the discussion. Just a suggestion.

Terminal velocity is the maximum and constant final speed a falling object can obtain. The value is dependent on the shape of the object, its mass, and the density of the medium it fall through. Assuming the OP was talking about earth air, and normal pool balls, the terminal velocity is about 100 mph as calculated previously. A balling ball, due to its high mass will have a higher terminal velocity (300mph or so).

Or you can tell me I'm confused. But I'm not. I'm just a mechanical engineer.

lol dude...I hope you are better in pool than in physics.

Cornerman
08-09-2017, 07:42 PM
lol dude...I hope you are better in pool than in physics.

You owe me an apology, but you won't give one.

Linwood
08-09-2017, 07:46 PM
It has minimal affect...a golf ball will hit the ground at the same time as a watermelon. In a vacuum a hammer and a feather will fall at the same rate.

There are simple equations for this, just run the math.

I never understand why people argue about well understood math.

The terminal velocity is inversely proportional to both the square root of the drag coefficient and the square root of the cross sectional area.

You can imagine things all day long that give lie to the idea -- an arrow and a bowl of the same mass for example.

But just think about two humans falling out of a plane. One aims down and dives, one goes into a spread eagle. You see it all the time during sky dives. They are both at terminal velocity (after a few seconds anyway), but going at wildly different speeds.

Just do the math. There's never a point in arguing math. Show your work. :)

Cornerman
08-09-2017, 07:48 PM
There are simple equations for this, just run the math.

I never understand why people argue about well understood math.

The terminal velocity is inversely proportional to both the square root of the drag coefficient and the square root of the cross sectional area.

You can imagine things all day long that give lie to the idea -- an arrow and a bowl of the same mass for example.

But just think about two humans falling out of a plane. One aims down and dives, one goes into a spread eagle. You see it all the time during sky dives. They are both at terminal velocity (after a few seconds anyway), but going at wildly different speeds.

Just do the math. There's never a point in arguing math. Show your work. :)

He doesn't understand the math. He doesn't understand the question.

Cuebuddy
08-09-2017, 07:54 PM
He doesn't understand the math. He doesn't understand the question.

Correct on both counts....he may not know who he has locked horns with;)

BC21
08-09-2017, 08:04 PM
There are simple equations for this, just run the math.

I never understand why people argue about well understood math.

The terminal velocity is inversely proportional to both the square root of the drag coefficient and the square root of the cross sectional area.

You can imagine things all day long that give lie to the idea -- an arrow and a bowl of the same mass for example.

But just think about two humans falling out of a plane. One aims down and dives, one goes into a spread eagle. You see it all the time during sky dives. They are both at terminal velocity (after a few seconds anyway), but going at wildly different speeds.

Just do the math. There's never a point in arguing math. Show your work. :)

Yep. I believe terminal velocity (the maximum speed an object reaches in free fall) happens when the drag (resistance to falling) becomes equal to the pull of gravity. All of this is dependent on the factors you and cornerman and others have mentioned, which is why different objects reach different terminal velocities at different times. Not sure how high you'd have to drop the ball from in order for it to have time to reach TV before it lands, but it can be calculated.

Math is awesome.

8ballr
08-09-2017, 08:08 PM
Correct on both counts....he may not know who he has locked horns with;)

Dude doesn't understand the laws of gravity.

Two objects of different mass only fall at the same rate in a vacuum. In the atmosphere, drag forces act on the object as it moves though the fluid (air). As velocity increases, these drag forces become larger. Terminal velocity is the point at which the drag force equals the force of gravity.

mikepage
08-09-2017, 08:10 PM
You're confused...nobody is talking about a vacuum here...only you. Terminal velocity is the same for most all falling objects of any mass...ie if you drop a golf ball and a bowling ball from a building they will hit the ground at the same time. The exception is if you drop a feather and a bowling ball...obviously the bowling ball will first...unless in a vacuum then they will hit at the same time...ie on the moon.

Even in a vacuum, the bowling ball will hit before the golf ball.

The reason a golf ball--or anything-- falls is because of a gravitational force exerted by the earth. But forces always come in pairs. By Newton's third law, the golf ball pulls on the earth just as hard as the earth pulls on the golf ball. As a result the earth accelerates toward the golf ball and comes to meet it a bit.

A bowling ball pulls way harder on the earth than does a golf ball, and so the earth comes further to meet it. And the time till they collide is shorter.

JohnnyOzone
08-09-2017, 08:43 PM
Even in a vacuum, the bowling ball will hit before the golf ball.

The reason a golf ball--or anything-- falls is because of a gravitational force exerted by the earth. But forces always come in pairs. By Newton's third law, the golf ball pulls on the earth just as hard as the earth pulls on the golf ball. As a result the earth accelerates toward the golf ball and comes to meet it a bit.

A bowling ball pulls way harder on the earth than does a golf ball, and so the earth comes further to meet it. And the time till they collide is shorter.

Seriously? what is the mass of either a golf ball or a bowling ball relative to the mass of the earth? Both are so negligable as to be effectively zero. I suppose that if they fell toward earth from an extremely long distance, and if the earth had no atmosphere, that it might be measurable.

I would hate for the earth to be pulled out of its orbit due to a really fat person jumping off of a high dive! :)

Cornerman
08-09-2017, 08:57 PM
Dude doesn't understand the laws of gravity.

Two objects of different mass only fall at the same rate in a vacuum. In the atmosphere, drag forces act on the object as it moves though the fluid (air). As velocity increases, these drag forces become larger. Terminal velocity is the point at which the drag force equals the force of gravity.

Most of us already knew this. And we answered the terminal velocity question correctly. You weren't part of "most of us." You still aren't. But, by all means, continued showing your vast ignorance.

8ballr
08-09-2017, 10:29 PM
Most of us already knew this. And we answered the terminal velocity question correctly. You weren't part of "most :Dof us." You still aren't. But, by all means, continued showing your vast ignorance.

Once again...
Btw, if you like talking about vacuums so much, maybe you should try selling them door to door. :D

Cornerman
08-09-2017, 10:59 PM
How many times can you be proven wrong in one thread? What is this 5 times already?
If you like talking about vacuums so much, maybe you should try selling them door to door. :D

Incredible. Not one time have you understood the question. I tutored Physics for over ten years. Please at least just stop making more of a fool of yourself.

Terminal velocity was the question. This is a Physics 101 question. A pool ball and a bowling ball and a marble and a penny have never had the same terminal velocity in earth's air. You've misunderstood the question, and you don't understand basic real-world physics.

When you're ready to eat crow, I've got the salt for you. Until then, you might want to keep quiet and read a bit.

Cornerman
08-09-2017, 11:15 PM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)
Well, hopefully you've waded through the BS. As has been calculated, it's about 100 mph, despite the attempts of the wannabe physicist who didn't get past 8th grade physical science.

Per the snapshots, here are various terminal velocities for different bodies with clearly different masses. Additionally, per Lindwood, attached is also the basic quadratic formula for terminal velocity of a pool ball sphere through air. I estimated the density to get ~170g mass.

Hope this gets what you're looking for.

Freddie <~~~ none accepted

Shannon.spronk
08-09-2017, 11:15 PM
Cornerman has this 100% correct. I am currently a tutor in physics and other things engineering and I graduate in December as a mechanical engineer. 8ballr you lost all credibility when you said that terminal velocity is 9.8 m/s^2. That Is acceleration and not velocity. Acceleration is the rate of change of velocity per unit of time. A velocity can never be an acceleration and vice versa.

Mr. Bond
08-09-2017, 11:36 PM
Using the terminal velocity equation below, and assuming a normal air density of 1.27kg/m3, and a drag coefficient of 0.5 for a sphere.....

V = √(2mg/pAc)

m = mass of CB = 170.1g
g = gravity = 9.8m/s2
c = drag coefficient = 0.5
A = area of falling object = 25.66cm2 (convert to meters = 0.002566m2)
p = air density = 1.27kg/m3 (covert to grams3 = 1,270g/m3)

Plug it all in and get 45.24m/s, or 101.2mph. Nobody can break the balls that fast!

Thank you

How far must the average pool ball fall before Terminal velocity is reached?

8ballr
08-09-2017, 11:38 PM
Cornerman has this 100% correct. I am currently a tutor in physics and other things engineering and I graduate in December as a mechanical engineer. 8ballr you lost all credibility when you said that terminal velocity is 9.8 m/s^2. That Is acceleration and not velocity. Acceleration is the rate of change of velocity per unit of time. A velocity can never be an acceleration and vice versa.

Ya I was getting ahead of myself...didn't realize I would have to spoon feed you guys the obvious. Terminal velocity according to the op's question would be the same for all objects regardless of mass. Do I need to explain why or can you "mechanical engineers" figure it out?

KMRUNOUT
08-10-2017, 12:58 AM
Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)

And how many feet would it take to reach it?

And, is that velocity faster or slower than the average break speed of an 8 ball player? ( or 9ball)

Not sure you understand what terminal velocity is. Without air resistance, I think most physicists would say the terminal velocity of a pool ball or anything else is the speed of light. Typically, the term "terminal velocity" refers to the maximum speed an object can reach under earth's gravity WITH air resistance. The air resistance is what imposes the limit on the speed of a falling object. A human being with clothing typical has a terminal velocity of anywhere from 120-140 mph. I would imagine a pool ball would be significantly faster than that. I'd take a stab in the dark guess that it is something like 200 mph. Hard to say though...I imagine a more dense object would likely have a higher terminal velocity than a less dense object, all other things being equal. It seems like a pool ball is more dense than a human being, although I may be wrong about this. It is surely harder on average, but maybe not more dense. A pool ball sized glob of fat probably weighs more than a pool ball. FOr some reason if I picture it falling at a fast speed, it seems the air would very much influence its fall. Maybe it doesn't have the density to fall as fast as a person, but it sure has a better shape I would think. But I would make a much more confident guess that it is MUCH MUCH faster than anyone can break.

KMRUNOUT

KMRUNOUT
08-10-2017, 01:21 AM
You're confused...nobody is talking about a vacuum here...only you. Terminal velocity is the same for most all falling objects of any mass...ie if you drop a golf ball and a bowling ball from a building they will hit the ground at the same time. The exception is if you drop a feather and a bowling ball...obviously the bowling ball will first...unless in a vacuum then they will hit at the same time...ie on the moon.

This is not at all correct. When you compare a golf ball and a bowling ball, you are selecting objects that share a number of qualities, and hence yield terminal velocities that are relatively close. However, you have already disproved your own claim with the example of the feather. Think about a ping pong ball, a beach ball, a 4x8 sheet of plywood, a lead ball bearing. They will all have different terminal velocities than a golf ball or a bowling ball.

It seems you are not understanding the term "terminal velocity".

Now a question to the people that actually understand physics: The "force of gravity" is the "same" for objects on earth because we are comparing objects that are of essentially negligible mass compared to the mass of the earth. But would it not be true that an *extremely* massive object would have a greater acceleration under gravity, in that the gravitational force exerted by the object on the earth would have an additive effect? I mean the whole m1m2/r^2...wouldn't an object that is 1/4 the mass of the earth "fall" with more acceleration? (Or rather "move towards the earth"). Is this right?

KMRUNOUT

KMRUNOUT
08-10-2017, 01:25 AM
lol dude...I hope you are better in pool than in physics.

This is getting good. Few things entertain me more than this sort of thing. I believe the equation is E=WR^2, where E is entertainment value, W is the amount the person is wrong, and R is the amount they think they are right. 8ballr is really maxing out the value of E here.

Edit: bonus points for the fact that the link says exactly what Freddie was saying.

KMRUNOUT

KMRUNOUT
08-10-2017, 01:35 AM
Ya I was getting ahead of myself...didn't realize I would have to spoon feed you guys the obvious. Terminal velocity according to the op's question would be the same for all objects regardless of mass. Do I need to explain why or can you "mechanical engineers" figure it out?

Ok I get it. We have been trolled. It almost seemed like this was simply a very ignorant person wallowing in their own foolishness.

Good one man, you got us. Now I feel like the idiot for not getting this sooner.

KMRUNOUT

BC21
08-10-2017, 04:20 AM
Ya I was getting ahead of myself...didn't realize I would have to spoon feed you guys the obvious. Terminal velocity according to the op's question would be the same for all objects regardless of mass. Do I need to explain why or can you "mechanical engineers" figure it out?

Lol. Because the OP stated "with no air resistance". But there is no terminal velocity without resistance. The object would continue to accelerate until it met the Earth. So I, and others, ignored the "no air resistance" in order to calculate a true terminal velocity. The real answer to the exact question would be: none - no terminal velocity

BC21
08-10-2017, 05:14 AM
Thank you

How far must the average pool ball fall before Terminal velocity is reached?

Are you planning a fabulous trick shot? Lol. I'd say you'd have to drop the ball from a little more than 100m (about 350ft). It would take it about 5 seconds, and terminal velocity would be reached at about the same time the ball crashes into the table or ground. A more advanced physics guy can probably calculate the exact values.

Texdance
08-10-2017, 06:34 AM
Ask a sky diver, they will know terminal velocity. It is somewhere in the 125mph range near sea level, for a near-round object with no special wind resistance like a diver falling without a parachute. Feathers, lifting bodies, gliders, and parachutes of course can fall slower depending on wind resistance generated by the item's shape. Thicker air at sea level slows the terminal velocity.

The average break shot is well under 30 mph. I've heard some pro or pros can break 31-32 mph, but that would be a very fast break.

There is a cool smartphone app (free?) to show players the actual speed of their break. You put the cueball on the head spot - center of the table, opposite the second diamond - and rack normally with the lead ball on the foot spot, Set the phone on the rail, set the app, and fire away. The phone hears the first and second contact and calculates speed based on the known distance between the head spot and foot spot.

So far my best effort is 26-something mph, and if I don't concentrate my break speed falls to under 24 mph. I believe pros can break faster, but not twice as fast.

The OP wrote "Can anyone tell me the terminal velocity of an average pool ball? (earth gravity, with no air resistance)"

When he mentioned something he called Terminal Velocity 'with no air resistance', he showed no understanding of what Terminal Velocity actually is:
...the velocity at which a falling body moves through a medium, as air, when the force of resistance of the medium is equal in magnitude and opposite in direction to the force of gravity.

or, the maximum velocity of a body falling through a viscous fluid.

So the initial question is a non-question, or ignorant question, or a troll, pick one.

8ballr
08-10-2017, 07:21 AM
Lol. Because the OP stated "with no air resistance". But there is no terminal velocity without resistance. The object would continue to accelerate until it met the Earth. So I, and others, ignored the "no air resistance" in order to calculate a true terminal velocity. The real answer to the exact question would be: none - no terminal velocity

The answer simply is less than c.

The same theory says that objects gain mass as they speed up, and that speeding up requires energy. The more mass, the more energy is required. By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed

BUT this is a moot point because...

g is only 9.81m/s/s on the Earth's surface. The inverse square law applies and, as you go further away, the acceleration decreases and decreases. At a 'great distance', the acceleration would be nearly zero!

Cornerman
08-10-2017, 08:19 AM
Ya I was getting ahead of myself...didn't realize I would have to spoon feed you guys the obvious. Terminal velocity according to the op's question would be the same for all objects regardless of mass. Do I need to explain why or can you "mechanical engineers" figure it out?

We got that immediately. But you went with complete nonsense that Terminal Velocity = acceleration due to Earth gravity. The rest of assumed "no additional resistance," and four posts already told him the question wasn't worded correctly.

From there you showed how little understanding you had of anything. We saw it, don't worry. "A little ahead of yourself" doesn't remotely come close to the situation.

Linwood
08-10-2017, 08:27 AM
The answer simply is less than c.

The same theory says that objects gain mass as they speed up, and that speeding up requires energy. The more mass, the more energy is required. By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed

This is moot.

If you are trying to think of terminal velocity as the speed at which an object dropped from a near infinite distance would strike the earth given that nothing else interfered (i.e. air, other planets or suns), this is simple to calculate and a small number relative to the speed of light, namely it is 11.2km/s, The speed of light is about 300,000km/s.

If I did my math right, that means the increase of mass from this falling-from-infinite-height is 0.00000007%. Good luck measuring that.

This is the escape velocity - they are an identical concept, basically one where all the energy from falling is converted into the equivalent potential energy, the latter is an integration from the earth's surface to infinite height where the gravitational force gets progressively weaker with height.

Slow college students do this derivation in first year physics; good ones do it in high school. A bit later they derive the special relativistic formula. (Well, they used to - now they learn to feel good about not being able to do math without asking Siri.)

We live today in the age of google -- people can find perfectly correct information that they can misapply and post authoritatively. :rolleyes:

8ballr
08-10-2017, 08:29 AM
We got that immediately. But you went with complete nonsense that Terminal Velocity = acceleration due to Earth gravity. The rest of assumed "no additional resistance," and four posts already told him the question wasn't worded correctly.

From there you showed how little understanding you had of anything. We saw it, don't worry. "A little ahead of yourself" doesn't remotely come close to the situation.

I answered the op's question as it was presented. You and others tried to change the parameters to fit your answers...that's called observation bias.

Cornerman
08-10-2017, 08:37 AM
I answered the op's question as it was presented. You and others tried to change the parameters to fit your answers...that's called observation bias.

This from a guy who gave this gem:

Acceleration to a to terminal velocity...which for a cueball or a marble or just about any object in a free-fall position is about 195 km/h.

Try to spin that answer. Hint: it doesn't follow that you understood anything yet.

8ballr
08-10-2017, 08:43 AM
This from a guy who gave this gem:

Try to spin that answer. Hint: it doesn't follow that you understood anything yet.

I have already dropped the mic...by the laws of the internet the discussion is now over. :)

Cornerman
08-10-2017, 08:55 AM
I have already dropped the mic...by the laws of the internet the discussion is now over. :)

Don't forget to return the salt.

pt109
08-10-2017, 09:38 AM
I have already dropped the mic...by the laws of the internet the discussion is now over. :)

How fast was the mic going at impact?

8ballr
08-10-2017, 09:44 AM
How fast was the mic going at impact?

Good question! Are we in a vacuum? jk
Assuming the mic weighs 1 kg and is dropped from 1 meter:

Speed at impact:4.43 m/s
or 15.94 km/h
Time until impact: 0.45 s
Energy at impact: 9.80 joules

https://www.angio.net/personal/climb/speed.html

Linwood
08-10-2017, 10:34 AM
Good question! Are we in a vacuum?

Of more interest is that the interest in this topic has been dropping as well. I has halved at each new posting, and was not high to begin with.

As the Engineer said, paraphrased, "interest is close enough to zero for practical purposes".

---- caution politically insensitive matter below ---

For those not familiar with the joke it is a variant on zenos' paradox. There's a game show and they bring out a mathematician and an engineer, both male. They then open a curtain and a gorgeous lady stands before them, equal distances from each.

They both cheer up considerably.

The host says "I will ring a bell periodically, and each time, you will each move half-way to this beautiful lady".

The mathematician immediately looks distressed, and sits down and cries.

The host asks why -- he says "if I can only move half-way each time, at finite intervals, I can never quite get there. I quit".

The Engineer however is grinning and happy. The host now asks him "why are you so happy, did you not hear? Do you not understand math?"

The Engineer just smiles and says "but I can get close enough for all practical purposes".

--- we now return to this thread unfortunately probably still in progress, with interest at terminal velocity for sure ---

08-10-2017, 10:54 AM
All I can imagine when asked about cueballs and terminal velocity. Is a published story tells of young men,in the quest of a bigger break made a interesting discovery. They removed the leadshot from a 12gauge shotgun shell,inserted the shell into the barrel chamber,stuck a modified shaft down the barrel,and let whitey loose. Wood splinters were everywhere. Whitey resembled humptydumpty and I believe paneling suffered schrapnel scarring! Perhaps a ear got pulled I just remember the breakshot.

Mr. Bond
08-10-2017, 10:56 AM
Yeah I goobed the question a little with the part about the air resistance. What I meant was, no additional wind or turbulence, not no air. Fortunately most of you understood my intent anyways.

So if a strong break can reach 30mph, approximately how high would I have to drop a ball from to reach 30mph?

Ghosst
08-10-2017, 11:00 AM
So if a strong break can reach 30mph, approximately how high would I have to drop a ball from to reach 30mph?

On a flat earth or a spherical one?

Linwood
08-10-2017, 11:00 AM
So if a strong break can reach 30mph, approximately how high would I have to drop a ball from to reach 30mph?

Approximately 30 feet and a fall of 1.4 seconds will get you to about 30 mph.

Getting a frozen rack standing on end to have it hit the lead ball is left as an exercise to the student.

pt109
08-10-2017, 11:10 AM
On a flat earth or a spherical one?

There's a good argument somewhere in there to refute Max Eberle's theory....
...but I'll leave it to more educated minds to pursue that.
..'course, he might not believe in gravity, either.

08-10-2017, 11:14 AM
If its a barbox cueball ,NASA couldnt predict where it would land.

Cornerman
08-10-2017, 11:48 AM
Yeah I goobed the question a little with the part about the air resistance. What I meant was, no additional wind or turbulence, not no air. Fortunately most of you understood my intent anyways.

So if a strong break can reach 30mph, approximately how high would I have to drop a ball from to reach 30mph?

Cornerman
08-10-2017, 11:54 AM
On a flat earth or a spherical one?

Near and dear to my heart. For a flat earth, if you're near the edges, balls would "drop" sideways-ish. As with the waterfalls .

And of course, with a flat earth, we'll throw out the earth gravitational constant since it wouldn't be constant on a flat earth model.

Freddie <~~~but I'm ignorant of such things

mikepage
08-10-2017, 11:55 AM
Yeah I goobed the question a little with the part about the air resistance. What I meant was, no additional wind or turbulence, not no air. Fortunately most of you understood my intent anyways.

So if a strong break can reach 30mph, approximately how high would I have to drop a ball from to reach 30mph?

lots of good stuff--and not so good stuff--aside, this may help.

The speed in mph is pretty close to 5.5 * square root(height in feet). So, for example from a height of 16 feet, it is 5.5*4, or 22 mph. This is a pretty fast break.

Here is a graph that shows the bigger picture.

Dropping from higher heights than shown here, the speed will start dropping off below this no-air prediction. But in this height range it is probably OK.

I don't know why you are asking, but if you have visions of building a cueball ramp to get consistent and predictable cueball speeds to model a break, then you will have to deal with fact your falling cueball might pick up a lot of forward spin as it goes from down to sideways. That is, a cueball in an actual break has in general relatively little spin for its high speed. The falling cueball may not.

Cornerman
08-10-2017, 12:02 PM
Just for anyone interested, I used the Break App for several breaks at the US Open 8-ball.

Fastest break I clocked was Thorsten at 25mph. Shane was mostly at 23-24mph. Dennis was around 22-23 (never hit 24), and Alex was consistently at 21.5ish.

Freddie <~~~ 20ish

Agent 99
08-10-2017, 12:07 PM
Can anyone tell me -- exactly what is gravity?

Isn't the concept really just a theory and not scientific fact?

Just wondering.

mikepage
08-10-2017, 12:16 PM
Can anyone tell me -- exactly what is gravity?

Isn't the concept really just a theory and not scientific fact?

Just wondering.

One of my favorite books of all time is called "The Character of Physical Law" and it is transcripts from lectures Feynman gave in 1964. The first chapter addresses essentially your question

http://people.virginia.edu/~ecd3m/1110/Fall2014/The_Character_of_Physical_Law.pdf

Agent 99
08-10-2017, 01:15 PM
One of my favorite books of all time is called "The Character of Physical Law" and it is transcripts from lectures Feynman gave in 1964. The first chapter addresses essentially your question

http://people.virginia.edu/~ecd3m/1110/Fall2014/The_Character_of_Physical_Law.pdf

Cool book .. read the first chapter and will read the rest later.

Here is a quote from the first chapter, page 14 -- "I have chosen for my special example of physical law the theory of gravitation, the phenomena of gravity."

So, the author confirms here that the gravity concept is in fact a theory, not scientific fact. He even refers to gravity as a "phenomena."

I do not know why he refers to this theory as a physical law .. not even sure what that means .. how can it be any kind of law if the force in question can not be defined?

He goes on to talk about the effects of this mysterious force on other matter, but in no way describes what gravity actually is.

I appreciate the link and look forward to reading the rest of the book, however the first chapter only confirms the existence of a force we call gravity, it in no way explains what gravity actually is.

Mr. Bond
08-10-2017, 01:18 PM
I don't know why you are asking, but if you have visions of building a cueball ramp to get consistent and predictable cueball speeds to model a break, then you will have to deal with fact your falling cueball might pick up a lot of forward spin as it goes from down to sideways. That is, a cueball in an actual break has in general relatively little spin for its high speed. The falling cueball may not.

Interesting you should say that.
This was all meant to be a theoretical discussion but I have indeed considered such a ramp before.
Actually, as you pointed out, it would have to be more of a "slide" than a ramp, but still not impossible to do.

Linwood
08-10-2017, 01:23 PM
Near and dear to my heart. For a flat earth, if you're near the edges, balls would "drop" sideways-ish. As with the waterfalls .

Well, not if you actually believe, the Flat Earth society (yes, there is one) says that gravity is a side effect of the earth accelerating upward:

https://wiki.tfes.org/Universal_Acceleration

You can't make this stuff up... well, I couldn't make it up.

Though... how about hollow earth? Ever figure out that one? If earth was a (say) 10 mile deep shell (assume spherical), and the inside was hollow (and it was somehow strong enough to exist in that form), how does gravity work on the inside shell? Do people stick to it upside down?

What's the terminal velocity of a pool ball dropped from 5 feet below (i.e. closer to the center) the shell? Assume normal atmosphere. How about dropped from the center of the shell?

Can anyone tell me -- exactly what is gravity?

Isn't the concept really just a theory and not scientific fact?

No, it's a democratically decided concept. You vote for it.

What happens is people line up at the top of a cliff. Those who think gravity does not exist are invited to step off and prove it.

This happened millennia ago; all those who voted for it to exist are our ancestors.

Though it may be time for a new election. :D

Agent 99
08-10-2017, 01:35 PM
Well, not if you actually believe, the Flat Earth society (yes, there is one) says that gravity is a side effect of the earth accelerating upward:

https://wiki.tfes.org/Universal_Acceleration

You can't make this stuff up... well, I couldn't make it up.

Though... how about hollow earth? Ever figure out that one? If earth was a (say) 10 mile deep shell (assume spherical), and the inside was hollow (and it was somehow strong enough to exist in that form), how does gravity work on the inside shell? Do people stick to it upside down?

What's the terminal velocity of a pool ball dropped from 5 feet below (i.e. closer to the center) the shell? Assume normal atmosphere. How about dropped from the center of the shell?

No, it's a democratically decided concept. You vote for it.

What happens is people line up at the top of a cliff. Those who think gravity does not exist are invited to step off and prove it.

This happened millennia ago; all those who voted for it to exist are our ancestors.

Though it may be time for a new election. :D

Actually you are describing the effects of the force called gravity when you illustrate people jumping off a cliff -- lol -- You have not defined in any way what that force actually is.

Thanks for the laugh !!

Linwood
08-10-2017, 01:42 PM
Actually you are describing the effects of the force called gravity when you illustrate people jumping off a cliff -- lol -- You have not defined in any way what that force actually is.

That's OK. I also haven't defined what "I" am, and how "I" know I exist, so knowing how "I" am held down to the earth is the least of my worries.

Prove you exist, and are not a figment of my imagination, and I'll define gravity for you.

Ghosst
08-10-2017, 01:46 PM
Can anyone tell me -- exactly what is gravity?

Isn't the concept really just a theory and not scientific fact?

Imaginary friends in the sky who tell you to kill each other over varying interpretations of a book written by hundreds of people and rewritten over 2000 years by thousands more *might* be a theory. It might be homicidal aliens too. No one actually knows. Therein is the difference between faith and science.

Further explained:

Gravity is observable, every single time. It is the attraction of two bodies, the force of which decreases (in two bodies with same mass in each experiment) as an inverse square of the distance between their centers. It can be observed, very easily, with two boats in close proximity in a harbor: leave them untied and they will drift together. The more massive the ships, the more quickly it will occur. Every object exerts gravity on every other object. The reason you jump and the Earth doesn't move up (it does, but not a measurable scale) to meet you is a function of the difference in mass.

None of this has anything to do with the OPs question though, to which I might ask, why do you want to know? Are you planning to drop a pool ball from an elevated structure onto the head of a Ram-Shot user? If so, don't leave fingerprints. Also, just video it and Bob or Freddie can discern the exact figures from there.

pt109
08-10-2017, 01:48 PM
Immanuel Velikovsky felt that gravity was an electromagnetic phenomenon.
He upset many experts in a few fields and was ostracized by many of his peers....
....but when Albert Einstein died, an opened book by Velikovsky was found on his desk.
...so some great minds did not find him irrelevant.

Agent 99
08-10-2017, 01:51 PM
That's OK. I also haven't defined what "I" am, and how "I" know I exist, so knowing how "I" am held down to the earth is the least of my worries.

Prove you exist, and are not a figment of my imagination, and I'll define gravity for you.

This is one of the few scientific type threads to appear on AZB -- your statement is so non-scientific that I am not able to respond to it.

You can 'believe' anything that makes you feel good or better about yourself and your environment .. everything is going to be alright .. ;-)

By the way .. you do not have to worry about proving anything to me.

Have a nice day.

Agent 99
08-10-2017, 02:05 PM
Imaginary friends in the sky who tell you to kill each other over varying interpretations of a book written by hundreds of people and rewritten over 2000 years by thousands more *might* be a theory. It might be homicidal aliens too. No one actually knows. Therein is the difference between faith and science.

Further explained:

Gravity is observable, every single time. It is the attraction of two bodies, the force of which decreases (in two bodies with same mass in each experiment) as an inverse square of the distance between their centers. It can be observed, very easily, with two boats in close proximity in a harbor: leave them untied and they will drift together. The more massive the ships, the more quickly it will occur. Every object exerts gravity on every other object. The reason you jump and the Earth doesn't move up (it does, but not a measurable scale) to meet you is a function of the difference in mass.

None of this has anything to do with the OPs question though, to which I might ask, why do you want to know? Are you planning to drop a pool ball from an elevated structure onto the head of a Ram-Shot user? If so, don't leave fingerprints. Also, just video it and Bob or Freddie can discern the exact figures from there.

I understand and agree with what you wrote here. But again, this is only describing the effects of gravity and not identifying what it actually is.

Why not just say that an object of greater density than it's surrounding environment will fall simply because it is heavier?

I would hope we could all agree that is a scientific fact ... and quite simple.

Did you know that Newton's gravity concept has been modified by different scientists as new discoveries made the original theory invalid? I remember that Albert Einstein was one of them.

Why do I want to know? Because I am always attempting to have a greater understanding of reality and the physical world that we live in. Simply seeking facts and the truth, not all that interested in theory's being used as a building block to ratify further scientific fact.

I am an open minded individual. If anyone can define what gravity actually is in scientific terms, I would be the first to thank him, as he would greatly further my knowledge and understanding.

BC21
08-10-2017, 02:06 PM
Imaginary friends in the sky who tell you to kill each other over varying interpretations of a book written by hundreds of people and rewritten over 2000 years by thousands more *might* be a theory. It might be homicidal aliens too. No one actually knows. Therein is the difference between faith and science.

Further explained:

Gravity is observable, every single time. It is the attraction of two bodies, the force of which decreases (in two bodies with same mass in each experiment) as an inverse square of the distance between their centers. It can be observed, very easily, with two boats in close proximity in a harbor: leave them untied and they will drift together. The more massive the ships, the more quickly it will occur. Every object exerts gravity on every other object. The reason you jump and the Earth doesn't move up (it does, but not a measurable scale) to meet you is a function of the difference in mass.

None of this has anything to do with the OPs question though, to which I might ask, why do you want to know? Are you planning to drop a pool ball from an elevated structure onto the head of a Ram-Shot user? If so, don't leave fingerprints. Also, just video it and Bob or Freddie can discern the exact figures from there.

Can't find a LIKE button, so.......:grin-square:

Linwood
08-10-2017, 02:08 PM
This is one of the few scientific type threads to appear on AZB -- your statement is so non-scientific that I am not able to respond to it.

You can 'believe' anything that makes you feel good or better about yourself and your environment .. everything is going to be alright .. ;-)

By the way .. you do not have to worry about proving anything to me.

Have a nice day.

Is it unscientific?

A lot of very scientific theories today wonder if time is an illusion.

Some very literate types wonder how we would tell if our existence turns out to be a simulation.

What is the origin of conciousness, can internet bots achieve it?

How can one tell the difference in a bot and a person? Maybe some of the players in this thread do not exist (as humans)? (Read about the Ashley Madison event).

Yes, my comment was somewhat unscientific, because a lot of the trolling statements are pretty unscientific.

You can pick apart any statement and find fodder for discussion, e.g. the phrase used that I was responding to was "scientific fact". What is a scientific fact? Science tends to rely on observations and hypotheses that explain them, which gain more and more credibility and in doing so might be then called theorems or laws but are they ever facts?

Even mathematics tends to be a closed system, starting with certain axioms which are accepted but not provable, to derive other theorems which are said to be "proven" but only to the degree the axioms are correct. Read about Gödel's incompleteness theorems.

To the original point: I would suggest that the reality of "I" is a lot less well understood, scientifically, than gravity.

mikepage
08-10-2017, 02:23 PM
Actually you are describing the effects of the force called gravity when you illustrate people jumping off a cliff -- lol -- You have not defined in any way what that force actually is.

[...]

Forget the word "fact" for a minute, because that get's people in trouble.

Let's say we have "observations" about which we agree.

---the apple falls from the tree
---the tide come in, then goes out, then comes in, then goes out ....

likely no disagreements here; also no explanations.

We might want to "explain" a collections of observations by proposing they are consistent with a broader, more fundamental generalization: gravity. So we would have a THEORY that the tides are explained by gravity.

Then we might see this gravity explanation not only is consistent the the observations we've made in the past. But we can predict new observations where we haven't yet looked and see if they check out. The theory is always tentative as an explanation, but it gets stronger the more observations that fit it.

So what about gravity? Can that be explained in terms of something broader and more fundamental? I don't know. Maybe, and maybe not. When we use the word "physical law," we are implying the buck stops here in terms of explanation: it is an end of the line of sorts--a broad generalization about the patterns in the observations we've made about world around.

You could call it God's will if you like. Or you can say it is what it is. Or you can search for broader, more fundamental pattern connecting a greater number of observations. Your call...

Ghosst
08-10-2017, 03:03 PM
I understand and agree with what you wrote here. But again, this is only describing the effects of gravity and not identifying what it actually is.

Here, again, is the difference between science and conspiracy. Conspiracy theorists have an explanation for every little detail of their theory. They don't prove anything, only rebut the works of others as they don't have original ideas of their own. Scientists don't assume their total knowledge because they aren't writing a fallacy, they are exploring the boundaries of collective human knowledge.

There is no, "This Is How Magnets Work (with particles) vol 2, ed:9", out there. We know they work. We understand why(ish). But the *exact* how, not so much. In that is the beauty of exploration and understanding. While once we thought a solar eclipse was the end of the world because we did not know what magic caused the day to turn into night, we now celebrate that rare chance to observe the corona (not the beer) to gain more knowledge of that life-giving, mid-range, cool-yellow, middle aged star in the center of our solar system. (Yes, that was a run-on sentence JAM; it was intentional to show a train of thought).

However, for the OP, the question remains. Why is the distance a cueball must travel in order to meet its' terminal velocity of import? Your silence, rather well placed I might add, intrigues me. I feel this mystery might involve a collection of neurons collectively firing through their synapses to resolve a pattern which I must gain superiority over in animal display of survival intelligence to be worthwhile. Much the same as the theory of the universe as a hologram and how machines could well have invented it, I feel that human desire to reach beyond my bounds. It's interesting to note though that a neuron, by itself, does little. A few hundred, and nothing. A few million, and life takes shape. They are less intelligent, on their own, than a calculator. And yet, we have cellular phones each with more power than the entire lunar landing mission in our hands connected together in a global network called the internet. Perhaps, dear friends, we are already through the looking glass and simply haven't noticed it.

What were we talking about again? Oh yeah, I lost 20-16 last night, but at \$5 a rack it was worth the lesson. I need to work on my fundamentals some more.

garczar
08-10-2017, 03:12 PM
Ya I was getting ahead of myself...didn't realize I would have to spoon feed you guys the obvious. Terminal velocity according to the op's question would be the same for all objects regardless of mass. Do I need to explain why or can you "mechanical engineers" figure it out?.............................................. ......................

AtLarge
08-10-2017, 03:53 PM
Just for anyone interested, I used the Break App for several breaks at the US Open 8-ball.

Fastest break I clocked was Thorsten at 25mph. Shane was mostly at 23-24mph. Dennis was around 22-23 (never hit 24), and Alex was consistently at 21.5ish.

Freddie <~~~ 20ish

Freddie -- I think I heard you say that app works off the time difference between two sounds -- tip hitting CB and CB hitting OB. The distance between CB and OB can differ quite a bit on break shots. How does the app account for that?

pt109
08-10-2017, 04:16 PM
Freddie -- I think I heard you say that app works off the time difference between two sounds -- tip hitting CB and CB hitting OB. The distance between CB and OB can differ quite a bit on break shots. How does the app account for that?

I much prefer the radar gun that was used long ago...
...it told you what speed the cue ball was traveling AS IT MET THE HEAD BALL...
...I been told that the cue ball is decelerating before it gets t the pack...so at the head
ball is really the pertinent info.

I was hearing some big speeds at a break contest at a Canadian bar championship
about 20 years ago...but they were being clocked only one diamond after it was hit...
....a little fake news was a problem even back then.

Agent 99
08-10-2017, 04:23 PM
Forget the word "fact" for a minute, because that get's people in trouble.

Let's say we have "observations" about which we agree.

---the apple falls from the tree
---the tide come in, then goes out, then comes in, then goes out ....

likely no disagreements here; also no explanations.

We might want to "explain" a collections of observations by proposing they are consistent with a broader, more fundamental generalization: gravity. So we would have a THEORY that the tides are explained by gravity.

Then we might see this gravity explanation not only is consistent the the observations we've made in the past. But we can predict new observations where we haven't yet looked and see if they check out. The theory is always tentative as an explanation, but it gets stronger the more observations that fit it.

So what about gravity? Can that be explained in terms of something broader and more fundamental? I don't know. Maybe, and maybe not. When we use the word "physical law," we are implying the buck stops here in terms of explanation: it is an end of the line of sorts--a broad generalization about the patterns in the observations we've made about world around.

You could call it God's will if you like. Or you can say it is what it is. Or you can search for broader, more fundamental pattern connecting a greater number of observations. Your call...

Excellent post. I suppose that I am some what old-school.

My call is to only credit veracity to observations that are made by observing controlled experiments that replicate the same effects each time the experiment is conducted.

I have nothing against a good theory - in fact theories are what lead to controlled experiments in order to produce a comprehensive understanding rooted in undisputable fact. -- Now you have a building block for extrapolation of new understandings.

I remember years ago, when mathematical statistics came to being. A good friend of mine, who is a remarkable mathematician, did not think much about the theory of statistics.

When I asked him about this 'new mathematical discipline' he laughed and said, "Statistics were invented so people would have a way to lie with mathematics."

I never forgot that, and wonder if the same is true with physical theories, when used as undisputable fact in order to claim a new factual break through, or to substantiate the validity of an unknown matter.

You summed it up perfectly, thanks again for the book.

Cornerman
08-10-2017, 04:46 PM
Freddie -- I think I heard you say that app works off the time difference between two sounds -- tip hitting CB and CB hitting OB. The distance between CB and OB can differ quite a bit on break shots. How does the app account for that?

You move the cueball on the app to where the breaker is set up. They all were breaking just off the head spot.

Cornerman
08-10-2017, 04:49 PM
Excellent post. I suppose that I am some what old-school.

My call is to only credit veracity to observations that are made by observing controlled experiments that replicate the same effects each time the experiment is conducted.

I have nothing against a good theory - in fact theories are what lead to controlled experiments in order to produce a comprehensive understanding rooted in undisputable fact. -- Now you have a building block for extrapolation of new understandings.

I remember years ago, when mathematical statistics came to being. A good friend of mine, who is a remarkable mathematician, did not think much about the theory of statistics.

When I asked him about this 'new mathematical discipline' he laughed and said, "Statistics were invented so people would have a way to lie with mathematics."

I never forgot that, and wonder if the same is true with physical theories, when used as undisputable fact in order to claim a new factual break through, or to substantiate the validity of an unknown matter.

You summed it up perfectly, thanks again for the book.Just a little perpsective, you just responded to a retired Physical Chemistry Professor that you're old school when it comes to sciences.

Cornerman
08-10-2017, 04:51 PM
I much prefer the radar gun that was used long ago...
...it told you what speed the cue ball was traveling AS IT MET THE HEAD BALL...
...I been told that the cue ball is decelerating before it gets t the pack...so at the head
ball is really the pertinent info.

I was hearing some big speeds at a break contest at a Canadian bar championship
about 20 years ago...but they were being clocked only one diamond after it was hit...
....a little fake news was a problem even back then.Interesting. I always thought the radar gun was showing peak velocity, including the entire path of the cueball to the rack.

AtLarge
08-10-2017, 05:06 PM
You move the cueball on the app to where the breaker is set up. They all were breaking just off the head spot.

Ah, so it's a graphic of a playing surface, and you can place the CB in the appropriate place on that surface. How about the head ball in the rack -- can it be moved, e.g., in 9-Ball with the 9-ball on the spot? I'd guess "yes," in order for the app to be usable for any shot on the table, not just break shots.

Cornerman
08-10-2017, 05:10 PM
Ah, so it's a graphic of a playing surface, and you can place the CB in the appropriate place on that surface. How about the head ball in the rack -- can it be moved, e.g., in 9-Ball with the 9-ball on the spot? I'd guess "yes," in order for the app to be usable for any shot on the table, not just break shots.

It's the Predator Break Speed App.

There is a way to set up custom distances, but moving the rack isn't a feature (that I know of).

Agent 99
08-10-2017, 05:20 PM
Just a little perpsective, you just responded to a retired Physical Chemistry Professor that you're old school when it comes to sciences.

I happen to be retired as well...

pdcue
08-10-2017, 05:22 PM
Interesting you should say that.
This was all meant to be a theoretical discussion but I have indeed considered such a ramp before.
Actually, as you pointed out, it would have to be more of a "slide" than a ramp, but still not impossible to do.

So, Will you call it a Galileo tribute slide:)?

Dale

LAMas
08-10-2017, 05:26 PM
"...earth gravity, with no air resistance)..."

Terminal velocity means that velocity at which the resistance due to air molecules hitting the object exactly equals the force of gravity. So in an absolutely perfect vacuum and a perfectly uniform gravitational field that extends throughout all space, the body would accelerate forever.

The speed is variable.

Mr. Bond
08-10-2017, 10:56 PM
" I am. I said.
To no one there."

- Neil Diamond

Texdance
08-11-2017, 10:59 PM
Near and dear to my heart. For a flat earth, if you're near the edges, balls would "drop" sideways-ish. As with the waterfalls .

And of course, with a flat earth, we'll throw out the earth gravitational constant since it wouldn't be constant on a flat earth model.

Freddie <~~~but I'm ignorant of such things

A dozen years ago we visited a Flat Earth Society combination ghost town and preserved village, somewhere along the Gulf Coast, can't remember and now can't find it on google. It was a fascinating little tourist diversion.

Inside the village meeting hall was a massive wooden curved beam and straightedge device, very well made, possibly by a boat builder. The device and some other info purported to prove the earth's flatness.

Most interesting, however, were the collection of small buildings ranging from shops to storage to dorms - apparently this community was self-supporting by the sale of goods made collectively. In that sense it was an experiment in social engineering also.

Sorta like azb, where even engineers ignore the viscous fluid requirement under the dictionary definition of 'terminal velocity' to try to make sense of a post.

I wonder if the OP could restate his query in light of the many replies, and let us know what use he intends to make of the information. Maybe he wants to build a ramp to experiment with break shot speed and location, where his ramp gives each shot a somewhat repeatable nature depending on the ramp height, spin applied at start, and positioning of the exit. I think 35' tall ramp to achieve a 30 mph break might be discouraging, though.

Mr. Bond
08-11-2017, 11:20 PM
Knowledge is it's own reward.
What you do with it is up to you.

jay helfert
08-12-2017, 02:27 AM
Now can we do a comparison of the terminal velocity of a Gold Crown table compared to a Diamond? :eek:

I have personally witnessed the aftermath of a Valley bar table being dropped from 30' high during the set-up stages for the U.S. Bar Table Championships in the late 90's at the Flamingo Hilton in Reno. We were using a crane to lift the tables one at a time into the third floor window of an upstairs ballroom when a table slipped from the restraining straps and fell to the ground. Fortunately the area underneath had been roped off to pedestrians, otherwise someone might have ended up in the morgue! The table crashed with a sound rivaling a hand grenade and sent debris flying as far as 100 yards away. We all had to take a long break after that to collect ourselves and thank our lucky stars that no one was close enough to get hit by the shrapnel. ;)

pt109
08-12-2017, 02:42 AM
Now can we do a comparison of the terminal velocity of a Gold Crown table compared to a Diamond? :eek:

I have personally witnessed the aftermath of a Valley bar table being dropped from 30' high during the set-up stages for the U.S. Bar Table Championships in the late 90's at the Flamingo Hilton in Reno. We were using a crane to lift the tables one at a time into the third floor window of an upstairs ballroom when a table slipped from the restraining straps and fell to the ground. Fortunately the area underneath had been roped off to pedestrians, otherwise someone might have ended up in the morgue! The table crashed with a sound rivaling a hand grenade and sent debris flying as far as 100 yards away. We all had to take a long break after that to collect ourselves and thank our lucky stars that no one was close enough to get hit by the shrapnel. ;)

I can just see the head lines....
CRANE BREAKS, DESTROYS TABLE

467195

pt109
08-12-2017, 03:10 AM
I just terminated a duplicate post with a fair amount of velocity.

Mr. Bond
08-12-2017, 05:37 PM

What if I took a ball and hung it from a 35ft string, then dropped it like a pendulum so it would "swing down" instead of fall.

How much difference would that make in the velocity, once it has dropped the 35ft, as opposed to a free fall.

8ballr
08-12-2017, 06:00 PM
What if I took a ball and hung it from a 35ft string, then dropped it like a pendulum so it would "swing down" instead of fall.

How much difference would that make in the velocity, once it has dropped the 35ft, as opposed to a free fall.

https://youtu.be/7OwsNqXm1b8?t=1m32s

Mr. Bond
08-13-2017, 12:55 AM
https://youtu.be/7OwsNqXm1b8?t=1m32s

I think I missed the point

mikepage
08-13-2017, 03:29 AM
What if I took a ball and hung it from a 35ft string, then dropped it like a pendulum so it would "swing down" instead of fall.

How much difference would that make in the velocity, once it has dropped the 35ft, as opposed to a free fall.

No difference

In either case all of what was previously potential energy (the mass lifted up 35 feet) is converted to kinetic energy--energy of motion.

greyghost
08-13-2017, 06:41 AM
Using the terminal velocity equation below, and assuming a normal air density of 1.27kg/m3, and a drag coefficient of 0.5 for a sphere.....

V = √(2mg/pAc)

m = mass of CB = 170.1g

g = gravity = 9.8m/s2

c = drag coefficient = 0.5

A = area of falling object = 25.66cm2 (convert to meters = 0.002566m2)

p = air density = 1.27kg/m3 (covert to grams3 = 1,270g/m3)

Plug it all in and get 45.24m/s, or 101.2mph. Nobody can break the balls that fast!

Yeah not even close lol. What's the record maybe 35 mph

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LAMas
08-13-2017, 09:46 AM
The post asked with no air resistance - in a vacuum. an academic question.

How about a tail wind to offset the air resistance?

greyghost
08-13-2017, 11:07 AM
The post asked with no air resistance - in a vacuum. an academic question.

How about a tail wind to offset the air resistance?

So it goes full meteor? Johnny flame balls

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