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Post by vergyltantor on Jul 11, 2021 22:16:25 GMT -5
Calculating projectile isn't just horizontal an vertical velocity’s (mph’ or ft/sec) example: a ball having initial velocity of 40 mph (58.667ft/s), at an initial upward trajectory of 2 degree’s , contacted at 9’ above court, will reach a max height of 9.06 feet, travel 46.30 feet, it will take .81secs to get there, So if i hit jump float at 40 mph contacting ball 9’ above court, it will travel 46.3 feet before hitting floor reaching a max height of 9.06 feet. This is the calculation for a projectile starting at a height above floor , receiving an initial horizontal velocity, and the upward angle of the projectile. From that you calculate m, time in air, distance traveled, max height achieved. Are you taking aerodynamic drag into account? Experience tells me that drag will slow the ball in all directions, but gravity effect the ball in a vertical direction. Calculations made in a vacuum vary wildly from those that take drag into effect, and with a low mass, high drag object like a volleyball this is especially true.
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Post by dodger on Jul 12, 2021 1:29:07 GMT -5
Calculating projectile isn't just horizontal an vertical velocity’s (mph’ or ft/sec) example: a ball having initial velocity of 40 mph (58.667ft/s), at an initial upward trajectory of 2 degree’s , contacted at 9’ above court, will reach a max height of 9.06 feet, travel 46.30 feet, it will take .81secs to get there, So if i hit jump float at 40 mph contacting ball 9’ above court, it will travel 46.3 feet before hitting floor reaching a max height of 9.06 feet. This is the calculation for a projectile starting at a height above floor , receiving an initial horizontal velocity, and the upward angle of the projectile. From that you calculate m, time in air, distance traveled, max height achieved. Are you taking aerodynamic drag into account? Experience tells me that drag will slow the ball in all directions, but gravity effect the ball in a vertical direction. Calculations made in a vacuum vary wildly from those that take drag into effect, and with a low mass, high drag object like a volleyball this is especially true.
Objects traveling short distances don't need to consider drag in calculations: of course drag would have an effect on distance traveled but for discussion its not necessary! Understood air slows the ball in both horizontal and vertical axis. We also know that spin effects distance traveled. Also materials and shape: example: Golf ball dimples are an example of manufacturers attempting to affect the forces of drag to improve ball flight and accuracy |
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Post by vergyltantor on Jul 12, 2021 2:51:35 GMT -5
I found a paper on the flight of 2 different Mikasa balls and a Molten ball that fits nicely into this discussion.
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes by Takehiro Tamaru, Shinichiro Ito and Masaki Hiratsuka at Department of Mechanical Engineering, Graduate School of Kogakuin University in Tokyo www.mdpi.com/2504-3900/49/1/146It is a free download of a short paper, no math required.  |
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Post by volleydadtx on Jul 12, 2021 9:17:59 GMT -5
I found a paper on the flight of 2 different Mikasa balls and a Molten ball that fits nicely into this discussion.
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes by Takehiro Tamaru, Shinichiro Ito and Masaki Hiratsuka at Department of Mechanical Engineering, Graduate School of Kogakuin University in Tokyo www.mdpi.com/2504-3900/49/1/146It is a free download of a short paper, no math required. Good read. They set the serve machine at 3.5 meters high, or 11.48 feet. I don’t know that they cited the net height. The higher the release point, the faster a serve can be, as the ball can be in descent immediately from release. |
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Post by oldnewbie on Jul 12, 2021 11:30:20 GMT -5
I found a paper on the flight of 2 different Mikasa balls and a Molten ball that fits nicely into this discussion.
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes by Takehiro Tamaru, Shinichiro Ito and Masaki Hiratsuka at Department of Mechanical Engineering, Graduate School of Kogakuin University in Tokyo www.mdpi.com/2504-3900/49/1/146It is a free download of a short paper, no math required. Good read. They set the serve machine at 3.5 meters high, or 11.48 feet. I don’t know that they cited the net height. The higher the release point, the faster a serve can be, as the ball can be in descent immediately from release. If the bottom of the ball is at 8 feet, a 45mph serve should clear a women's net and land on the back line over the shortest path end line to end line. That is completely discounting all drag and deceleration, which should make it even easier to achieve. Is 8 feet realistic? I just measured myself and I serve 6 inches below my max touch. Hitting 6 inches below max touch and hitting the ball with your fingers at the top of the ball, it would take a player who touched 8 feet a 12 inch jump to serve at 8 feet. Reasonable for a whole lot of players. At 42mph you can do it while serving from a height of 7 feet. Again, that is the worst case with no drag and no deceleration while traveling the shortest possible distance of 18m. There are lots of projectile calculators online. They are fun to play with. |
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Post by sonofdogman on Jul 12, 2021 12:31:54 GMT -5
What is the difference in airspeed of a European volleyball vs an African volleyball?
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Post by vbcoach06 on Jul 12, 2021 13:07:18 GMT -5
What is the difference in airspeed of a European volleyball vs an African volleyball? One farts in your general direction. |
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Post by silverchloride on Jul 12, 2021 13:31:55 GMT -5
What is the difference in airspeed of a European volleyball vs an African volleyball? One farts in your general direction. Nice, Monte Python reference. |
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Post by newenglander on Jul 12, 2021 15:25:30 GMT -5
I can say from personal experience that trying to serve a ball from wall to wall over a distance of 140' (being not productive at a boys volleyball practice) that drag is a major factor and hitting a ball with no spin will prevent the ball from travelling that distance easily. With a little side spin I could hit it that far (and moderate spin puts too much of a curve into it). Slight backspin helps but it was harder to control. My point is only that you can't do the calculations with accounting for wind resistance.
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Post by dodger on Jul 12, 2021 15:27:46 GMT -5
I found a paper on the flight of 2 different Mikasa balls and a Molten ball that fits nicely into this discussion.
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes by Takehiro Tamaru, Shinichiro Ito and Masaki Hiratsuka at Department of Mechanical Engineering, Graduate School of Kogakuin University in Tokyo www.mdpi.com/2504-3900/49/1/146It is a free download of a short paper, no math required. Good read. They set the serve machine at 3.5 meters high, or 11.48 feet. I don’t know they cited the net height. The higher the release point, the faster a serve can be, as the ball can be in descent immediately from release. There is discussion on VT often on difference of passing international ball and ball used collegiately: but the international ball is designed with seams and texture to effect ball flight: i seem to remember when they changed ball a reason given was this ball design had the most reliable for ball flight. The japan study reminded me of that discussion when ball changed |
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Post by volleydadtx on Jul 12, 2021 15:45:52 GMT -5
Good read. They set the serve machine at 3.5 meters high, or 11.48 feet. I don’t know that they cited the net height. The higher the release point, the faster a serve can be, as the ball can be in descent immediately from release. At 42mph you can do it while serving from a height of 7 feet. Again, that is the worst case with no drag and no deceleration while traveling the shortest possible distance of 18m. There are lots of projectile calculators online. They are fun to play with. I haven't been able to replicate that with the serving machine. At 45 mph at contact, the ball would slow 8.5 MPH to 34.5 mph as it falls to the ground. I'm going to tinker with it some more tonight to see if I can make it happen. But if you are calling it 42 mph at contact, I can see that happening, as someone else here said the ball is slowing 1 MPH per 7 feet. So from end to end, assuming that is accurate, the ball would slow approx. 8.5 mph before hitting the floor. That puts you in the low 30s MPH, which is what I have replicated. |
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Post by oldnewbie on Jul 12, 2021 16:56:44 GMT -5
At 42mph you can do it while serving from a height of 7 feet. Again, that is the worst case with no drag and no deceleration while traveling the shortest possible distance of 18m. There are lots of projectile calculators online. They are fun to play with. I haven't been able to replicate that with the serving machine. At 45 mph at contact, the ball would slow 8.5 MPH to 34.5 mph as it falls to the ground. I'm going to tinker with it some more tonight to see if I can make it happen. But if you are calling it 42 mph at contact, I can see that happening, as someone else here said the ball is slowing 1 MPH per 7 feet. So from end to end, assuming that is accurate, the ball would slow approx. 8.5 mph before hitting the floor. That puts you in the low 30s MPH, which is what I have replicated. The radar gun is a big variable. How accurate is it and how far after it leaves the machine is the speed really being measured? Since the ball slows a fair amount, you could be 2-4 MPH higher than you think out of the machine. Serving at a real 49mph would be dramatically different than 45mph. Not sure how to check, other than with other people's different type and quality of radar gun, or high speed video if you've got it. The math for ideal ballistics is pretty clear. What is not so clear is how a VB actually flies. Intuitively I would expect that the direction of movement due to the float would be arbitrarily in any direction, but do the aerodynamics of a volleyball actually work that way? I have no idea. Does shooting a ball from rollers differ in any meaningful way from compressing a ball with your hand to launch it forward? Again, no idea. |
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Post by oldnewbie on Jul 12, 2021 17:16:02 GMT -5
This is mildly interesting. A video from pocket radar that shows a team (college? Club? Shirts say GB and they are at the Marquette gym) serving repeatedly, with a decent percentage above 40 and reaching as high as 43 (during the time I watched). Hard to tell most of the time the quality of the dead float and whether the balls were in
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Post by vergyltantor on Jul 12, 2021 17:55:13 GMT -5
Measuring the speed of the ball at the time of release is not a simple matter. The equipment needed to measure this is difficult to set up and calibrate unless you know a mechanical engineer or expert in the equipment that is looking for a project. I can't think of a way for a layman to do it accurately, and I question the need to have that number for any reason other than curiosity. For training purposes I would think that finding a maximum speed setting in whatever scale the machine provides, then introduce variation in speed, spin and direction as necessary to make the training meaningful would give the best results.
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Post by sonofdogman on Jul 12, 2021 19:27:16 GMT -5
The radar gun is a big variable. How accurate is it and how far after it leaves the machine is the speed really being measured? Since the ball slows a fair amount, you could be 2-4 MPH higher than you think out of the machine. Serving at a real 49mph would be dramatically different than 45mph. Not sure how to check, other than with other people's different type and quality of radar gun, or high speed video if you've got it. The math for ideal ballistics is pretty clear. What is not so clear is how a VB actually flies. Intuitively I would expect that the direction of movement due to the float would be arbitrarily in any direction, but do the aerodynamics of a volleyball actually work that way? I have no idea. Does shooting a ball from rollers differ in any meaningful way from compressing a ball with your hand to launch it forward? Again, no idea. Thank you for this. I've just been making fun of this whole thread. But you are actually thinking critically and asking the right questions. Now go sully up some other threads with your rational nonsense. |
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