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Influence of a humidor on the aerodynamics of baseballs

  1. Dec 4, 2007 #1


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    Influence of a humidor on the aerodynamics of baseballs
    Edmund Meyer, John Bohn
    17 pages, 6 figures
    (Submitted on 3 Dec 2007)

    "We investigate whether storing baseballs in a controlled humidity environment significantly affects their aerodynamic properties. To do this, we measure the change in diameter and mass of baseballs as a function of relative humidity (RH). We then model trajectories for pitched and batted baseballs to assess the difference between those stored at 30% RH versus 50% RH. The results show that a drier baseball may be expected to curve slightly more than a humidified one, and that the drier ball will also likely travel slightly less far when batted. We discuss consequences of these results for baseball played at Coors Field in Denver, where baseballs have been stored in a humidor at 50% RH since 2002."

    I would surmise that drier balls favor the pitcher,
    if they indeed take a curve better and, when hit, don't go as far.

    Conversely, damper balls might be supposed to favor the batter.

    EDIT: I got the effect backwards. Pitchers like the damper balls.

    I was under the impression that humidors were originally invented to store cigars, back in the days of serious cigar-smoking. Here is another use for humidors.
    Last edited: Dec 4, 2007
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  3. Dec 4, 2007 #2


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    Surprising they didn't measure the elasticity...
  4. Dec 4, 2007 #3


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    Elasticity/resiliency is one property/factor affected by humidity, the other is likely surface roughness.
  5. Dec 4, 2007 #4


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    I would have assumed the humid ball would be softer, therefor absorbing more of the impact from the bat, which would result in the ball not traveling as far as a harder, dry ball.

    I assume the balls are kept in a humidor to prevent the leather from cracking?

    Edit: Ah, the story behind the ball humidor, a pair of leather boots.

    Last edited: Dec 4, 2007
  6. Dec 4, 2007 #5


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    Pretty interesting story in Evo's link. They mention that the older balls stored at the park before humidors were actually falling under regulation weights due to the drying! I wouldn't have thought they would have THAT much water content in the balls. It makes you think that maybe storage conditions should be standardized across all parks. There are enough other variables that the storage of the balls shouldn't be one of them when it's something much easier to control (and how many of the team owners would be storing their cigars alongside the balls? :biggrin:)
  7. Dec 5, 2007 #6
    The elasticity as a function of humidity had already been studied, in The Physics Teacher, Vol. 42, p.89 (Sept. 2004).
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