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Post by mikegarrison on Aug 31, 2011 8:59:21 GMT -5
Personally, as a coach, I wonder about the value of variation in service styles among a team. For example, I probably had my best serving team ever this year in club--had a couple of nice jump top servers, three good standing float servers, and a jump floater. I made sure to arrange them so that there was variation between most of the servers. Better yet would seem to be one player who can vary her own serves and be effective with each of them.
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Post by lonewolf on Aug 31, 2011 9:40:42 GMT -5
Is the women's side going to adopt some version of the dimpled ball (similar to the Mikasa used in international ball)? I heard that thing dances around like no other and makes long time players feel like freshmen again (when they're using it outdoor anyway)! What level of the women's side? FiVB women use the Mikasa ball (at younger age levels around the world too). And in Norceca, I believe most are using the new Molten international ball. On an interesting note, Men's NCAA DI/II will be transitioning to a R/W/B version of the Molten international ball.
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Post by novotnis21 on Aug 31, 2011 9:44:03 GMT -5
Personally, as a coach, I wonder about the value of variation in service styles among a team. For example, I probably had my best serving team ever this year in club--had a couple of nice jump top servers, three good standing float servers, and a jump floater. I made sure to arrange them so that there was variation between most of the servers. Better yet would seem to be one player who can vary her own serves and be effective with each of them. I agree. I sometimes coach my team by having a server serve jump top until the other team figures out how to handle it then I have them switch to the float with some stank on it. Our aces per set went up and the other team just got frustrated.
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Post by The Bofa on the Sofa on Aug 31, 2011 9:53:26 GMT -5
I am trying to understand more about the dimpled ball. The effect of dimpling is to create turbulent airflow, which ultimately reduces wind resistance and consequently reduces the effect of air on the ball, hence reducing the amount of movement (see: golf balls; if they were smooth, they would be far harder to control than they are)
So what happens with the dimpled ball that messes people up? Is it because it comes faster than they expect or something?
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Post by BearClause on Aug 31, 2011 10:48:34 GMT -5
I am trying to understand more about the dimpled ball. The effect of dimpling is to create turbulent airflow, which ultimately reduces wind resistance and consequently reduces the effect of air on the ball, hence reducing the amount of movement (see: golf balls; if they were smooth, they would be far harder to control than they are) So what happens with the dimpled ball that messes people up? Is it because it comes faster than they expect or something? I remember seeing some video (forgot the source) of a Japanese variety show, where the hosts had a manufacturer make an undimpled golf ball. The compared it to the otherwise identical production version. I don't think the accuracy was the issue (the hosts were lousy golfers) but the dimpled ball easily traveled more than twice as far. The following article mentions the reduction in drag, as well as the effect of backspin on creating lift. www.scientificamerican.com/article.cfm?id=how-do-dimples-in-golf-baI don't golf, but have been to a few golf tournaments. The sound of a ball going by is strange. Sizzling bacon or an air leak is about the closest description I can think of. I'm pretty sure it's due to the dimples.
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Post by The Bofa on the Sofa on Aug 31, 2011 10:56:37 GMT -5
I am trying to understand more about the dimpled ball. The effect of dimpling is to create turbulent airflow, which ultimately reduces wind resistance and consequently reduces the effect of air on the ball, hence reducing the amount of movement (see: golf balls; if they were smooth, they would be far harder to control than they are) So what happens with the dimpled ball that messes people up? Is it because it comes faster than they expect or something? I remember seeing some video (forgot the source) of a Japanese variety show, where the hosts had a manufacturer make an undimpled golf ball. The compared it to the otherwise identical production version. I don't think the accuracy was the issue . No, accuracy is absolutely affected because the Coriolis effect is reduced in turbulent flow. My slice would be far worse with a smooth ball. But as you note, the distance is also decreased.
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Post by mikegarrison on Aug 31, 2011 11:22:23 GMT -5
What is going on here is a characteristic of spheres (or cylinders) in fluid flow. I'll simplify a bit.
Laminar (non-turbulent) flow around an object has less drag than turbulent flow. But turbulent flow has more energy. Because turbulent flow has more energy, it can follow "adverse pressure gradients" better. That means that turbulent flow remains attached to the surface of the ball on the back side of it, while laminar flow separates more easily.
The end result is that a smooth ball punches a bigger hole through the air than a rough ball, so the rough ball actually has less drag.
However, the actual amount of roughness required for optimum flight depends on the speed of the ball and the size of the ball (and also the altitude, the temperature, the humidity, and many other factors).
If a ball (or cylinder) has spin on it, that spin sets up a circulation in the air. Circulation is the mechanism that causes lift. So a top-spin ball generates negative lift and dives toward the ground faster than gravity alone would cause it to do. (Back-spin causes positive lift. Baseball home run hitters try to hit just under the center of the ball, giving it a back-spin that helps it carry over the fences.)
The "float" part of a float serve comes from the fact that the actual point of flow separation is dynamic. If the flow separates a little further along the surface of the ball on one side versus the other, that will cause an asymmetric force on the ball and it will be pushed in one direction. The more irregular the ball is, the more pronounced this will be, but even a perfectly smooth sphere will have some randomness in its flight path.
My guess (and this is only a guess) is that if these new balls exhibit more "float" that what is really happening is that the difference between the seams and the panels of the ball is bigger. If the separation is resisted on the panels but triggered on the seams, then the seams will work a bit like the stitches of a baseball. As the ball slowly rotates, first the seams will be prominent one one side and then they will be prominent on the other side. This will cause the ball to first dart one way, then to change and dart in the other direction.
If volleyballs did not have seams and panels, float serves would behave very differently than they do now. (Or so I guess, without actually doing any experimentation on the idea.)
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Post by Not Me on Aug 31, 2011 11:24:31 GMT -5
I love that ball. I've also noticed that it severely penalizes players who can't/don't pass jump floats with their hands. one should always pass float serves with their hands. and if your opponent is very good at passing floats with their hands, it's probably better to serve them topspin jumps... No, not at all. Most women should never use their hands to receive serve. They simply aren't strong enough to control the ball effectively. If you notice in the women's game, there was a movement when the rules changed to use their hands all the time. Over time, coaches have changed their focus. Why? Because using hands to receive serve is not nearly as effective for women as is using their platform.
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Post by baywatcher on Aug 31, 2011 11:32:31 GMT -5
Watched the Cal tourney this last weekend. All the Cal servers hit hop floats, not jump floats. Still had arc to get over the net and very few had real knuckle action. The other teams consistently got 3 balls to the setter. Cal was able to rely on athleticism and talent at the net to win, but when they start playing teams with deceptive setters and mujltiple hitters Cal better not be lulled into thinking they are hitting hard serves.
The best jump floats seem to have staying power, continuing on a relative straight line as they approach the returner, rather than naturally dipping down into the platform. Courtney Thompson from Washington seemed to be one of the best at creating that action
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Post by lonewolf on Aug 31, 2011 14:28:07 GMT -5
Personally, as a coach, I wonder about the value of variation in service styles among a team. For example, I probably had my best serving team ever this year in club--had a couple of nice jump top servers, three good standing float servers, and a jump floater. I made sure to arrange them so that there was variation between most of the servers. Better yet would seem to be one player who can vary her own serves and be effective with each of them. I think both can be important. If a team only has to see 1 type/tempo of serve, it becomes much easier to pass as the brain has less decisions to make and things to pay attention to.
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Post by lonewolf on Aug 31, 2011 14:29:39 GMT -5
one should always pass float serves with their hands. and if your opponent is very good at passing floats with their hands, it's probably better to serve them topspin jumps... No, not at all. Most women should never use their hands to receive serve. They simply aren't strong enough to control the ball effectively. If you notice in the women's game, there was a movement when the rules changed to use their hands all the time. Over time, coaches have changed their focus. Why? Because using hands to receive serve is not nearly as effective for women as is using their platform. I think you're term 'most' can be misleading. At the collegiate and international levels I think the bigger issue deals with hand size to control the ball as well as range with strength to cover the fast deeper serves along with the high seam serves.
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Post by mikegarrison on Aug 31, 2011 15:05:08 GMT -5
I remember seeing some video (forgot the source) of a Japanese variety show, where the hosts had a manufacturer make an undimpled golf ball. The compared it to the otherwise identical production version. I don't think the accuracy was the issue . No, accuracy is absolutely affected because the Coriolis effect is reduced in turbulent flow. My slice would be far worse with a smooth ball. But as you note, the distance is also decreased. FYI, there is no Coriolis effect of any significance on a golf ball. That has to do with the rotation of the Earth. I think you may be thinking about the Magnus effect. Surface roughness is probably going to enhance the circulation in the air due to the spin. The SciAm article suggests this, and so does my intuition about the physics involved. If that's true, the dimpled ball is going to be more sensitive to sidespin, not less sensitive.
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Post by BearClause on Aug 31, 2011 15:50:39 GMT -5
No, accuracy is absolutely affected because the Coriolis effect is reduced in turbulent flow. My slice would be far worse with a smooth ball. But as you note, the distance is also decreased. FYI, there is no Coriolis effect of any significance on a golf ball. That has to do with the rotation of the Earth. I think you may be thinking about the Magnus effect. Surface roughness is probably going to enhance the circulation in the air due to the spin. The SciAm article suggests this, and so does my intuition about the physics involved. If that's true, the dimpled ball is going to be more sensitive to sidespin, not less sensitive. Again, after watching several golf tournaments, I notice a late break on a ball from side spin. It might even be intentional in some cases.
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Post by mozie on Aug 31, 2011 15:54:33 GMT -5
Our youth teams here in Ontario, Canada use the Mikasa ball they use in FIVB indoor (the blue and yellow one). Huge amount of float on that ball. Makes a big difference in passing. My DD's team played in the US last winter and noticed a big difference in the speed of the serve when not using the dimpled ball. Serves come much, much harder and faster. The dimpled ball allows more rallies, I believe. I like it, but feel like our kids are at a disadvantage when playing in the US.
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Post by mikegarrison on Aug 31, 2011 16:16:39 GMT -5
FYI, there is no Coriolis effect of any significance on a golf ball. That has to do with the rotation of the Earth. I think you may be thinking about the Magnus effect. Surface roughness is probably going to enhance the circulation in the air due to the spin. The SciAm article suggests this, and so does my intuition about the physics involved. If that's true, the dimpled ball is going to be more sensitive to sidespin, not less sensitive. Again, after watching several golf tournaments, I notice a late break on a ball from side spin. It might even be intentional in some cases. Are you talking about in the air or when on the ground? In the air there is no such thing as a "late break" due to spin. What is perceived as a "break" is just the result of a constant acceleration. Since the distance from a straight line (ie. "break") is a function of the acceleration and the (time of flight)^2, most of the distance moved to the side happens at the end of the trajectory. It's the time-squared term coming in to play. But there is no real "break," as in a point where the ball suddenly starts moving sideways. The "float" or "knuckle" phenomenon is different. In that case, there actually can be a side-force suddenly applied to the ball late in the trajectory that wasn't there earlier.
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