mark cuban sheds light on the new ball

[nowagimp]

I hope this doesn't set JCSunsfan off again. At least he has the self-knowledge to include himself...

nowagimp, "One that I think is important, having played some ball, is that the deformation of the new ball is 30%(?) lower. This means that it behaves more elastically under collision, like a superball(in the limit)."

Where did you get the information that the new ball deforms less than the old one? In any case, the fact that it does not bounce back as much as the old one indicates that it is less like a super ball than the old one.

In the report, it stated that deformation was 30% less in the new ball, meaning it is more elastic, like a superball. No suprise here, its made almost entirely of elastomer, unlike a leather ball. A more elastic ball means more variable return velocities with different collision energies(hard, soft dribble). By the way ESPN is reporting that cubans tests indicate that it is not like the old ball, and it has 30% more imprecision in the bounce. Sounds like Cubans spin is different than ESPN's.

"It doesnt bounce back as much as the old one": Actually this depends on inflation pressure, but at a single inflation pressure the return velocities will vary more with incident velocity variation with an elastic ball(the new one). The deformation of the ball constitutes an inelastic energy absorbtion.

 

[elindholm]

It's not clear how the deformation is being measured of even what it means. They report that the new ball bounces less than a leather one. How is the energy difference accounted for? Unless the new ball radiates more heat on impact (which seems unlikely) or bounces louder (which no one has reported), the larger energy loss must be through small movements in the surface of the ball (edit: or within the surface, at the molecular level), which then dampen out over time as trace amounts of heat and sound. So apparently they are using "deformation" to mean something distinct from this, but I don't understand what.

 

[Mulli]

So will I be impressive this year when I point out that the ball's depression looks diminished?

 

[elindholm]

So will I be impressive this year when I point out that the ball's depression looks diminished?

If you can see that with your own eyes, heck yeah, I'll be impressed. But then, I don't have HDTV.

 

[nowagimp]

I hope this doesn't set JCSunsfan off again. At least he has the self-knowledge to include himself...

nowagimp, "One that I think is important, having played some ball, is that the deformation of the new ball is 30%(?) lower. This means that it behaves more elastically under collision, like a superball(in the limit)."

Where did you get the information that the new ball deforms less than the old one? In any case, the fact that it does not bounce back as much as the old one indicates that it is less like a super ball than the old one. As far as elasticity goes, they are both close to perfectly elastic as they do keep returning to their original shape - they'd be the devil to play with if they didn't. I don't think elasticity per se has anything to do with how well a ball bounces - a ball made out of 'memory foam' wouldn't bounce to speak of but it would eventually return to its original shape so it is quite elastic. IIRC, nerf balls behave much like that.

In an elastic collision, kinetic energy 1/2(mv)^2 is preserved for the system. Since the ground isnt moving, its the velocity of the ball that is preserved. Surely memory foam is not very elastic, as nearly all motion stops after collision. A superball however is very elastic, velocity is preserved when thrown against a hard immovable surface. The question is: how much energy is absorbed(not preserved) in the collision and how does this change with different incident velocities. My logic states that inelastic ball deformation(does not "reshape" on the timescale of the collision) absorbs energy and the inelastic deformation increases with incident velocity. The new ball inflated to a lower pressure deforms less than a leather ball. Perhaps I am wrong, but its just classic physics. The key is whether the ball returns to its original shape within the timescale of the collision(very fast). You can lower the psi of the ball, slowing velocities, but its the change in return with incident velocity that is important here not the absolute velocity. Its also why leather balls are inflated to higher psi for similar return velocity to a composite ball in a drop test, theyre less elastic.

 

[Errntknght]

nowagimp, "In the report, it stated that deformation was 30% less in the new ball, meaning it is more elastic, like a superball."

Its hard to discuss this when you say something is from the report and I can't find it. I did a search on the article and the letter sequence 'deform' did not appear. I also found three occurences of '30' but not were about deformation or compression. What they said about 'compression' is this:

(6) We have performed compression tests of all the balls. The data is being analyzed. Qualitatively, we find that the leather balls compress more easily under the same load, compared to the synthetic balls. The compression is linear over reasonable range of forces; we are in the process of quantitatively determining the elasticity.

If it really is in the article why don't you quote it for me...

 

[Errntknght]

We seem to have different ideas of what elastic and elasticity mean so I looked it up in some dictionaries & encyclopedias online. The general definition of elastic was something that tended to return to its original size and shape after exterior forces were removed. Oddly enough, physics has the same definition for elastic.

However, elasticity is not a measure of how close something came to returning to its original size and shape, which is what I thought. In fact, I couldn't find anything that mentioned elasticity, as a measureable quantity, except for the physics of solids and there elasticity equals the amount of change of size per unit of force applied. Although the basketballs are not in the realm of solids, applying this idea, the old ball has higher elasticity than the new one because it changes size, or at least, compresses more than the new one under the same force (according the report, as I quoted above). That also means that 'memory foam' and nerf balls have high elasticity as they compress very easily. Obviously, you meant something quite different than this definition. The speed at which somethings resumes its original size and shape is not mentioned, as you will see.

From Wikipedia the entry for elasticity:
Elasticity is a branch of physics which studies the properties of elastic materials. A material is said to be elastic if it deforms under stress (e.g., external forces), but then returns to its original shape when the stress is removed. The amount of deformation is called the strain.

Modeling elasticity

Under small stresses many solids' strains are roughly proportional to the stresses they are undergoing. The constant of proportionality (sometimes known as the elasticity), is given by the inverse of Young's modulus of elasticity, which is a measure of stiffness.

 

[elindholm]

The term "elastic" takes on a specialized meaning when discussing collisions. An elastic collision is one in which kinetic energy is conserved. In an inelastic collision, some kinetic energy is "converted into internal energy in at least one body" (Wikipedia, with similar language in other online references I found).

Here's an example from my freshman physics course: Take two air hockey pucks, going the same speed in opposite directions, and run them into each other. If they have equal mass and everything is lined up right, they will bounce back in the directions they came, maintaining the same speed. But if you encircle their perimeters with velcro, they will stick together on impact and most (potentially all, but good luck with that) kinetic energy will be lost to the velcro bond. Note that this could be a fully inelastic collision even if the pucks and velcro show very high elasticity.

 

[nowagimp]

The term "elastic" takes on a specialized meaning when discussing collisions. An elastic collision is one in which kinetic energy is conserved. In an inelastic collision, some kinetic energy is "converted into internal energy in at least one body" (Wikipedia, with similar language in other online references I found).

Here's an example from my freshman physics course: Take two air hockey pucks, going the same speed in opposite directions, and run them into each other. If they have equal mass and everything is lined up right, they will bounce back in the directions they came, maintaining the same speed. But if you encircle their perimeters with velcro, they will stick together on impact and most (potentially all, but good luck with that) kinetic energy will be lost to the velcro bond. Note that this could be a fully inelastic collision even if the pucks and velcro show very high elasticity.

Eric gets it, Kinetic energy is conserved: 1/2 mv^2. Since the mass is not changing and you have the immovable surface, its just the velocity of the ball. Dribble with greater energy and the ball will come back at equally high energy. Elastic materials(Elastomers) and elastic collisions are defined differently. As Errntknght stated, elastomers recover their original shape after being deformed. In the collision, the recovery of the material must happen on the timescale of the collision(almost instantaneous), meaning that memory foam will not behave elastically in any rapid collision. Recovery of the material after the collision still results in the loss of energy(KE not conserved) and is defined as an inelastic collision. Elasticity can be a problem with a basketball. Try dribbling a superball(worst case scenario), its hard to control. Add to that 30% greater inconsistency and you may have a very difficult situation.

 

[Errntknght]

When I finished watching the game last night I realized I hadn't once thought about the new ball being in play. That tells me that it can't be drastically different than the old one. In the threads I read, I don't think anyone mentioned instances where they noticed the ball behaving peculiarly, either.

 

[elindholm]

The Suns had a few cases of fumblitis that I thought might be attributable to the new ball. It's also true that both teams shot extremely well to open the game, when the ball was dry, and then tailed off as the game progressed, although the effect was more dramatic for the Suns. I wouldn't trust subjective impressions one way or the other, but there were certainly enough things to go on that I wouldn't be comfortable declaring the case closed.

 

[nowagimp]

The Suns had a few cases of fumblitis that I thought might be attributable to the new ball. It's also true that both teams shot extremely well to open the game, when the ball was dry, and then tailed off as the game progressed, although the effect was more dramatic for the Suns. I wouldn't trust subjective impressions one way or the other, but there were certainly enough things to go on that I wouldn't be comfortable declaring the case closed.

Good catch Eric on the dry ball at the beginning of the game. Perhaps it had something to do with the suns flawless opening. The suns had 16 of the 21 turnovers in the second half, a time when everyone will be sweating profusely, it may or may not have contributed, they were obviously playing badly. Very few fast(quick catch and release) catch and shoot 3's were made by either team, most of the threes came off the dribble or on deliberately set up shots. Odom, at times, had time for a cup of tea before lining up the shot from the perimeter. The lakers took their time setting up shots, probably critical with a potentially slippery ball. I think enough data will be in by the all-star break to make an objective assessment. To say there is no difference now is just silly, unsubstantiated and certainly not objective.

 

[Errntknght]

nowagimp, "Elastic materials(Elastomers) and elastic collisions are defined differently. As Errntknght stated, elastomers recover their original shape after being deformed."

Naturally, I said nothing about elastomers because I didn't even know what they were. Apparently I'm not the only one as the materials I mentioned are not elastomers - this is the dictionary definition of the term:
e·las·to.mer n. Any of various polymers having the elastic properties of natural rubber.

nowagimp, "Recovery of the material after the collision still results in the loss of energy(KE not conserved) and is defined as an inelastic collision."

Of course - the reason I mentioned memory foam and nerf balls was precisely to demonstate that elastic materials do not necessarily give rise to elastic collisions or even remotely close. I have to admit I wasn't able to follow much of what you said but you did seem to be attributing the difference in rebound height to the difference in the elasticity of the new and old style balls. Thus I searched mentally for something that was elastic but whose time of recovery was very slow which would make it obvious that time of recovery was the critical factor, not the elasticity per se. It was nice to see that my point got through.

Interestingly, the time of recovery can be too fast as well as too slow in some collisions - though it is not so easy to demonstrate. Golf ball and golf club collisions are one case that many people are somewhat familiar with - if you use a high compression ball (highly resistant to compression) with limber shafted clubs, the ball rebounds so quickly from the club face that much of the energy that is stored in the flex of the shaft is not transferred to the ball. (Of course, one could also say that the shaft is too slow to rebound.) As any golf pro will tell you, you need to match the two to get the most elastic collision. (Surely you've heard golf pros say that.) I'd better mention that I'm aware swing speed figures into it as well or that will probably get belabored, too.

This could have some relevance to the basketball testing they carried out. While we think of the floor as being perfectly rigid, it is not. Many peoples knees, mine for example, can quickly detect the difference between the elasticity of concrete and wood floors. Perhaps the result would be the same on a wood floor as on concrete but I wouldn't be a bit surprised if there was a significant difference.

 

[Errntknght]

Eric, The Suns had a few cases of fumblitis that I thought might be attributable to the new ball. It's also true that both teams shot extremely well to open the game, when the ball was dry, and then tailed off as the game progressed, although the effect was more dramatic for the Suns. I wouldn't trust subjective impressions one way or the other, but there were certainly enough things to go on that I wouldn't be comfortable declaring the case closed."

I hope they keep the option open of returning to the old ball for a while. But I have to admit I was somewhat surprised that no differences leapt out at me. We should hear more and more about it if the players are having difficulties with the ball, even its not obvious to us onlookers. As far as the Suns go, I remember lots of games where it looked like every rebounding ball was as slippery as eel.

 

[nowagimp]

nowagimp, "Elastic materials(Elastomers) and elastic collisions are defined differently. As Errntknght stated, elastomers recover their original shape after being deformed."

Naturally, I said nothing about elastomers because I didn't even know what they were. Apparently I'm not the only one as the materials I mentioned are not elastomers - this is the dictionary definition of the term:
e·las·to.mer n. Any of various polymers having the elastic properties of natural rubber.

nowagimp, "Recovery of the material after the collision still results in the loss of energy(KE not conserved) and is defined as an inelastic collision."

Of course - the reason I mentioned memory foam and nerf balls was precisely to demonstate that elastic materials do not necessarily give rise to elastic collisions or even remotely close. I have to admit I wasn't able to follow much of what you said but you did seem to be attributing the difference in rebound height to the difference in the elasticity of the new and old style balls. Thus I searched mentally for something that was elastic but whose time of recovery was very slow which would make it obvious that time of recovery was the critical factor, not the elasticity per se. It was nice to see that my point got through.

Your dictionary definition of elastomer is so terse as not to have obvious information. Its actually less informative than just saying that elastomers are materials having elastic properties. What are the properties of natural rubber, is it obvious? Rubber is a "high elastomer" or "highly elastic material" that exhibits almost pure elastic behavior on a stress/strain curve. Memory foam is actually a viscoelastic polymer, not an elastic one, the viscous part actually makes it less elastic, its a bad example of an elastomer, or "elastic material" as you put it, but dont seem to be able to make the jump that an elastomer IS an elastic material. The description of a viscoelastic polymer is probably beyond the scope of this discussion as you do not have a material science background(otherwise you wouldnt have looked up "elastomer" from a dictionary).

The goal of a new basketball design is NOT necessarily to have an elastic collision, unlike a golf stroke. The physics of golf club/ball collisions, like basketball bounces are NOT high physics, and gold pros are not especially knowledgable in classical physics, they're parrots of the engineers that design the clubs/balls, without the technical background. The discussion of golf ball design is not germaine to the evaluation of the properties of a new basketball which is supposed to(stern paraphrased, dont look it up) behave like, but more consistently than, the old one. I'm putting this one to rest as the discussion has apparently not been productive. I just assumed you knew more than you did, my bad.

I've had years of this stuff in undergraduate engineering/chemistry and graduate school, I dont need to look it up in dictionaries or cliffs notes. Sorry I couldnt reach you on it.

 

[Mulli]

Your dictionary definition of elastomer is so terse as not to have obvious information. Its actually less informative than just saying that elastomers are materials having elastic properties. What are the properties of natural rubber, is it obvious? Rubber is a "high elastomer" or "highly elastic material" that exhibits almost pure elastic behavior on a stress/strain curve. Memory foam is actually a viscoelastic polymer, not an elastic one, the viscous part actually makes it less elastic, its a bad example of an elastomer, or "elastic material" as you put it, but dont seem to be able to make the jump that an elastomer IS an elastic material. The description of a viscoelastic polymer is probably beyond the scope of this discussion as you do not have a material science background(otherwise you wouldnt have looked up "elastomer" from a dictionary).

The goal of a new basketball design is NOT necessarily to have an elastic collision, unlike a golf stroke. The physics of golf club/ball collisions, like basketball bounces are NOT high physics, and gold pros are not especially knowledgable in classical physics, they're parrots of the engineers that design the clubs/balls, without the technical background. The discussion of golf ball design is not germaine to the evaluation of the properties of a new basketball which is supposed to(stern paraphrased, dont look it up) behave like, but more consistently than, the old one. I'm putting this one to rest as the discussion has apparently not been productive. I just assumed you knew more than you did, my bad.

I've had years of this stuff in undergraduate engineering/chemistry and graduate school, I dont need to look it up in dictionaries or cliffs notes. Sorry I couldnt reach you on it.

You lost me at "your dictionary"

 

[elindholm]

You lost me at "your dictionary"

Is that the pure opposite of "You had me at 'Hello'"?

 

[Mulli]

Is that the pure opposite of "You had me at 'Hello'"?

I suspect that more than one of you scientific smarties are making up words and sneaking them into this thread as an inside joke. Elastomer? Come on.

 

[elindholm]

The amount of deformation a material undergoes in collision is poorly correlated with the elasticity of the collision in which it is involved. A clear example would be a spring with a low k (Hooke's Law constant). Mount the spring horizontally and slide a block into it (on the proverbial frictionless table, of course). The spring will compress a lot, then return all of the energy to the block as it decompresses.

But on the other side of the spectrum you have sponge balls and the like, which absorb the kinetic energy of the collision and then dissipate it (mainly as heat, I would guess) before springing back into shape. The sponge ball and the spring undergo comparable amounts of deformation, but the sponge ball collision is highly inelastic, while the one with the spring is (in principal) fully elastic.

 

[schutd]

I remember I used to like reading posts from Elindholm. E, I don't even know who you ARE anymore...

 

[Mulli]

I remember I used to like reading posts from Elindholm. E, I don't even know who you ARE anymore...

Really, I think E's computer has taken him over like Cartman's trapper keeper.

 

[elindholm]

Hey, at least I'm not being called arrogant and hostile with every other post...

But seriously, this is like connecting with a former self. Many, many years ago, I did a lot of physics. Then I changed fields into something frivolous and bogus, which may have been a mistake. So this gives me a chance to remember what it was like before I decided to throw my life away.

Usually a couple of days are all I need to get the reminiscing out of my system...

 

[schutd]

Hey! Me too! NT/2000 Admin to line cook. NICE!

 

[se7en]

I suspect that more than one of you scientific smarties are making up words and sneaking them into this thread as an inside joke. Elastomer? Come on.

I feel left out, as science was not my forte. However as a marketing/advertising guy, “Elastomer” sounds like a term that refers to customer satisfaction or return rate of customers. Okay, I know this is a “stretch”…

 

[msdundee]

I've been really interested reading this thread although most of the technical discussion is far beyond me.

Although I haven't heard many further comments on the new ball from players -- beyond the initial complaints, that is -- the boards will probably have lot of posts on that subject this year, with a tendency to feel that excessive TOs and sloppy ball handling in games might be a result of the change.

i can see the logic of that thinking but still have a problem with it, for one reason: all the players on the floor are playing with the same ball at any given time. Shaq was very vocal about not liking the new ball. As a team the Heat had a crummy game last night but can't very well blame it on the ball when the Bulls were obviously not having any trouble with it. In any case, if one team is floundering and the other team's shooting the lights out, there are bigger issues at hand.

Our game, for example. Suns were crazy good in the first quarter and LA looked awful. The next three quarters were just the reverse, and all ten players were playing with the same ball. The new ball absorbs moisture through the course of the game but I don't think anyone's inclined to think that LA just passes and shoots better when the ball gets wet and slippery.

One thing: it does make sense that some players will have more of a problem adapting to the change depending on their role in ballhandling, but that shouldn't take too long. Sounds like it's here to stay, at least for this year.