Slashdot Mirror
5000 fps Camera Reveals the Physics of Baseball
concealment sends this quote from an article at The Physics of Baseball "This clip from Game 4 shows Marco Scutaro hitting the ball right near the tip of the barrel. The amplitude of the resulting vibration is so large that the bat breaks and the ball weakly dribbles off the bat. Note that the bat splinters toward the pitcher. The reason is that when the ball hits the barrel tip, the barrel of the bat bends backward toward the catcher and the center of the bat bulges forward toward the pitcher. That is the natural shape of the fundamental vibrational mode of the bat. Since the fracture occurs near the center which is bulging outward, that is how the bat splinters, as the wood fibers on the pitcher side of the bat are stretched to the breaking point. If the ball had impacted the bat near the center, the center would have bulged toward the catcher, as in the Yadier Molina clip. Had the vibrational amplitude been strong enough in the Molina case, the bat would have splintered toward the catcher."
First pitch!
Great, way to make the game orders of magnitude longer.
http://webusers.npl.illinois.edu.nyud.net/~a-nathan/pob/HighSpeedClips.html
I could not see the images (seems slashdotted), but recently I saw this very interesting slow motion video of light itself:
here
pop-POP!
It even is so slow that when I tried to visit the site provided by the URL... It timed out on me!
Now, THAT is slow!
rm -rf --no-preserve-root /
Awww, come on there is a bunch of awesome physics stuff in there!
From a real physics-type guy: http://www.acs.psu.edu/drussell/bats.html
The bat doesn't break the way they describe.
1) It doesn't bend in the middle, it bends close to the fixed end (where it is being held).
2) What they describe is not the fundamental mode shape of a held bat. They are describing a free-free beam, but bats are usually held.
3) It does bend similar to its fundamental mode shape. But it's not breaking due to vibration. It's being deflected by an impulse load and breaking.
Simple engineering, and they got it wrong.
In some of the pictures, the bat looks like it is actually bent forward, toward the ball, when the ball hits it. Does anyone have an explanation for that? It's especially evident in the pic of the breaking bat. Is this just a motion thing that the camera doesn't catch well, or is there a physical reason that the bat would bend forward instead of backward? http://www.wired.com/rawfile/wp-content/gallery/fox-baseball/BROKEN-BAT.jpg
Would love to see some slow-mo pics of this, but I think we need more than 5000fps to see it:
http://what-if.xkcd.com/1/
"Get a bicycle. You will not regret it, if you live." - Mark Twain, "Taming the Bicycle"
Nuff said...
Yup - if you've ever wondered how the whole "breaking concrete with your fist" thing works this is a good example. If the impact is hard enough the concrete (bat) takes most of the energy and converts it into heat and breaking electromagnetic bonds (AKA 'breaking'), so the ball falls away limply or your fist doesn't break. Hit it in the wrong place though, and the ball takes all the energy (home run) or your fist does (hospital run).
Please consider this account deleted, I just can't be bothered with the spam anymore.
You would THINK they would have added a video to the article.
Perhaps I could learn to understand some of my exes behavior in bed with this technology...
'When the Going gets Weird, the Weird turn Pro.' - Hunter S. Thompson
Does anyone else think that the game of baseball survived the 50's and 60's simply because math and science could utilize it to teach their subjects? I don't see baseball as a game, but of a boatload of data and statistics.
They may use a camera that can run up to 5,000fps, but that's not the frame rate that was being shot.
There is no reasonable way to shoot high frame rates at night in the lighting conditions that exist in ballparks. Remember that stadium lights only actually project light 60 times per second, and not all of them fire at the exact same time (different power phases, feeds from different transformers and substations, etc). So while in sunlight you can shoot at 5,000fps (though no one does because it's impractical with the limited amount of time you have between pitches to show a replay), in large-scale HID (et al) lighting environments you can't shoot much more than 600-1000fps and still achieve a reasonable image quality. (Note that a referenced article in TFA says they shot at 3,000fps, but I still have major doubts that the captured clips or even the original clip which aired on television was actually shot at 3k FPS.)
And it's not just the frequency of the light, it's the amount. Zoom lenses lower the light that hits camera CCDs SIGNIFICANTLY. We experiment with high-speed cameras at long distances (center field pitch follow) quite regularly, and the result is incredibly underwhelming in anything other than direct sunlight. Though I will say, watching the movement and flight pattern of the pitch at high framerate in daylight is pretty spectacular.
Here (pdf) is an interesting whitepaper written by Grass Valley about the development of their super slow motion cameras, and the difficulties involved (flicker control, data rate, SNR, etc). The interesting reading begins on page 2. Note that this is NOT the camera used in the clips, the camera referenced is only doing 180fps - but you can extrapolate the complications presented in shooting 3000fps in HID lighting. (Side note: The referenced camera is the industry standard for smooth slow motion replay at 180fps. Ever notice that really smooth low-endzone NFL replay angle, or that definitive mid-1st MLB replay angle of the throw to first beating the runner? That's this camera.)
And in case you were wondering, the actual camera they used is here, though it was modified by a third party company to run at a higher frame rate.
There's more to it than just chemical bonds, it has a lot to do with how the internal structure distributes the energy from an impact. Concrete without reenforcing is brittle, a surprisingly short length supported at each end will snap under its own weight. Wood is fibrous, it's much easier to split in one direction than the other, the fibers give wood a much greater ability to deform than concrete. Notice that none of the strongman stunts use plywood, cross-laminated timber doesn't split easily in any direction, structurally it's much stronger than either non-reenforced concrete or ordinary timber.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
The campus has plenty of bandwidth, but the server it's on is one poor little box over in the nuclear physics lab. I'm just across campus and can't even get to the main nuclear physics site.
We broke his server. Pieces of it spewed out all over the infield.
If Slashdot were chemistry it would look like this:Cadaverine
...the importance of extension at the point of contact.
Don't we have trillion FPS cameras in development that can literally record light moving?
Not only is a variable being ignored its nearly the central reason for all the hoopla in this story. For all the millions of dollars wasted on major league players you would think that holding the main tool of the game properly would be a given but its not. Old timers from the dawn days of baseball knew this but it seems to have been forgotten sometime in the past 50 years. If these yahoos that call themselves pros really wanted to pound the ball they would learn how to hold the damn bat properly and not in such a way that it flexes excessively or breaks, both of which is an incomplete transference of the energy from batter to ball. The bat has a grain like all wood and this grain runs along the side of the bat at 90 degrees to the label. Holding the bat with the label up or down causes this area of bat to be the main contact area. "With the grain" the bat is much stronger and stiffer transferring more of the batters' energy to the ball and of course flying further. "Across the grain" the wood is weaker and more likely to flex or break as the fibers deform. No one has ever broken a bat "with the grain." In the bat breaking sequence you can clearly see the label is nearly square on to the direction of the pitch. The other vids aren't as easy to see the orientation of the bat but the excessive flex is telling. This "researcher" needs to find a player who knows how to hold the bat properly and repeat said observations. Then he will discover what the old timers who played in cornfields knew a century ago.
Power tends to corrupt, and absolute power corrupts absolutely.
The author originally wanted to use the New York Yankees as the focus... However, he was unable to capture enough examples of Yankee batters making contact with a baseball during the ALCS to complete the study.
Correct me if I'm wrong (although that would seem to go without saying), but what does an old timer using (most likely) an ash bat have to do with a young whipper snapper swinging maple? Don't they, I don't know, have different structure?
The math is way more complicated than that. No 100mph pitch is ever 100mph when the ball hits the glove. The initial velocity is 100mph, but due to wind resistance and other forces it can slow 12mph easily before it reaches the mound, 60ft after its initial release. This is why before MLB's Pitchtrax system different radar guns always gave different readings - they would pick up the ball at different points on its journey and thus at different speeds (leaving out the variable of calibration). You can actually get some really amazing raw pitch data using MLB's "Gameday" webpage during games. It will show you release velocity, velocity at contact, and a lot of other cool pieces of info (inches of break, etc).
10k FPS is impractical from every standpoint... data storage, image quality, lighting, and most importantly - playback. It would take 166 seconds at 59.97fps to play back a single second of video. We're lucky if we get 25 seconds between pitches to show a replay, not including the time to cue the clip up, the replay wipe in and out, etc. It might be cool to look at and analyze at some point down the road, or for the "wow" factor for the camera company and the mod company, but for a broadcast it seems pointless. Not that it's the first piece of pointless technology I've ever seen forced on us......
However, I do work baseball, do live in Detroit, and will be working the World Series games here (3, 4, 5). I'm going to seek out some additional info directly from the guys who run it this weekend.
I'm one of the camera designers (posting as AC 'cause i have no /. account).
The shots aired were at 5kfps during the day and 3kfps under lights. Anything much lower would not have really shown the bat bending etc. The actual impact would have looked better at 10kfps or more,
Yes, it's really the lighting that limits the speed, but these cameras are pretty sensitive; and they were used with fast (f2 or f2.8) lenses.
If you look closer, especially at the blurred background, you can see there is quite a bit of noise there - that shows the sensitivity was cranked up.
You're both wrong, it's all about how effectively you can focus your Chi, grasshopper.
Does anyone else think that the game of baseball survived the 50's and 60's simply because math and science could utilize it to teach their subjects? I don't see baseball as a game, but of a boatload of data and statistics.
No. The reason that Baseball thrived in the 50's and 60's was because the expansion teams in the west coast, the breaking of the black barrier and televised games and the press surrounding the "home-run" battles.
I doubt in the 50's and early 60's, many math and science teachers used baseball to teach their subjects . For math at that era, all the rage was "new-math" which emphasized stuff like set-theory and alternate number bases (not statistics). The physics in baseball is more about complex "pitching" and ball transport physics which is above what most people studied. Applying occam's razor, the simpler explanation that baseball's success was more likely due to tv and news-cycles (and a lesser extent local west-coast teams to cheer for).
FWIW, actual sabermetrics didn't really take off until after this book Percentage Baseball. Although it was published in 1964, it wasn't until early '70s and the use of computers that sabermetrics was really going enough to dribble down to the masses...
Viewing that page with 4 big animated gifs is a fail in chrome; can't animate, can't scroll, but ie did just fine.
Is it the segment with the fewest low-order nodes, so that impact there can set up only high-frequency, low-amplitude vibration?
That's funny. People in HEMA, WMA, and MARE have known about vibrational nodes in longswords for 20 years. This is nothing new, and not even useful anymore. Way to be lat to the physics party.