8 ms·

A cool article, laid out to be readily understandable for everyone. Missing from the discussion, though, is a description of the change in the moment of inerti

• ComputerGuru 9y ago
  It's funny, because based off the header image on that page [0], that's what I expected the discussion to be about. The center of gravity in those four samples is hugely off. [0]: https://espnfivethirtyeight.files.wordpress.com/2018/03/juiced_coresplitpair_silo-2.jpg?quality=100&strip=info&w=2048 https://espnfivethirtyeight.files.wordpress.com/2018/03/juic...
  • venning 9y ago
    If you scroll down further in the article, you'll see that those are cropped images of the cores. The cropping is off-center, not the cores. Otherwise, they would wobble terribly when thrown or hit.
    • ComputerGuru 9y ago
      No, I understand that. But look closely at the x-ray/CT and you'll notice that the rubber is nowhere near even around the core. The background images appear to actually be a video or something, but here's a screenshot I took: https://share.neosmart.net/View/Index/nfgSDo.png https://share.neosmart.net/View/Index/nfgSDo.png The two balls in the first column (so one old and one new) have a pretty symmetric distribution, but look closely at the others. Some are ridiculously uneven.
      • da_chicken 9y ago
        Yeah, but that doesn't matter here because it's present in both the newer era balls and the older era balls. We also know that seven of these are used baseballs, meaning they could very well be deformed or off center from use. There's a reason that they only use a baseball for about 8 pitches. (https://www.foxsports.com/other/story/major-league-baseballs-have-a-short-shelf-life-062912 https://www.foxsports.com/other/story/major-league-baseballs...)
        • jimnotgym 9y ago
          In cricket the same ball is used for 480 balls (depending of format). Initially the new hard ball is seen as an advantage to the fielding side as a bowler gets more bounce and deviation from the hard seam, but a batsman can also hit it further. There is also the phenomenon of swing (a bit like the curve ball in baseball) which is accentuated by the fielders polishing one side of the ball. As the ball ages and softens it's bounce becomes more true and therefore it favours the batting side. Often towards the end of its life the ball develops 'reverse-swing' where it curves the opposite way. They have to keep the 'rough side' of the ball completely dry to do this, so all fielders have to keep their hands dry. Penalties have been applied to players trying to alter the condition of the ball. Different brands of ball are polished differently and swing at different times. Some even have a lacquer which takes a while to come off and start swinging at all why I think this is relevant 1) The aerodynamic effects of the kind polish applied dramatically affect performance 2) Since wear on the ball is critical to the long format games, the fans don't get to take one home and sell it on ebay, even if they catch a six (ball hit into the crowd) :( The significant change in cricket hitting has been massively heavier bats, which used to be made of compressed willow to preserve their life (a whole season for a pro), but are now made of unpressed willow and considered disposable. The unpressed bats work much like corked baseball bats are supposed to, and have transformed the game. Slow-bowlers, like spin bowling where the bowler spins the ball to alter its flight and make it move when bouncing, have to be exceptional now or they get smashed into the car park!
          • danieltillett 9y ago
  • colanderman 9y ago
    The moment of inertia can change without a change in the center of gravity. Think ring vs. disc. I suspect this is what the GP was talking about.
• snovv_crash 9y ago
  Moment of inertia changes will also wildly affect a slightly off-center hit, as well as how hard it is to catch the resulting spinning ball.
• tomcam 9y ago
  I really appreciate your spin on this article. sorry