Experiments

Harder To Hit Homerun With Humid Baseballs

posted: 04/11/12
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As seen in "MythBusters: Baseball Special"
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Finding: PLAUSIBLE

Explanation: Since 2002, in an effort to reduce the high frequency of home runs hit in their high-altitude ballpark, the Colorado Rockies baseball team has been storing its baseballs in a climate-controlled humidor. But will a baseball steeped in a humid environment really sail for the fences with less fervor than a dry one? The MythBusters stepped up to the plate and found there may be some truth to this controversial myth.

One thing's for sure, storing a baseball in high humidity will cause it to absorb water. This "soak factor" makes humid baseballs heavier, but can it reduce bounce-ability when they connect with a bat? Determining a humid ball's "bounciness" means measuring its coefficient of restitution (COR), which is the time it takes a baseball to regain its shape after being hit. Unfortunately for home-run heavies, the more humid a ball becomes, the lower its COR is. The lower the COR, the slower a ball leaves the bat and the shorter the distance it travels.

There are so many variables in baseball hitting — including air pressure, wind speed, temperature and pitch velocity — that it's hard to confirm this myth definitively. But the MythBusters' findings show that the difference between batting a dry baseball and a humid one can mean the difference between an out and a home run. Seems a humid baseball just can't bounce back, but this myth can.

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