The statement in the text

D. Maximum height reached by the ball as a result of its collision with the bat's center of percussion, backed up by Mr. Ruth's 48 horsepower energy. The height attained will be greater on a clear day than on one when the air is full of moisture.

My response

I have already commented on the horsepower and the center of percussion, so no need to comment any further. However, the last statement is the one I want to challenge. The author claims that, in effect, there will be less air resistance on a clear (presumably dry) day than on a humid day. As a physicist, he really ought to know better. All other things equal (as the author is fond of saying in his article), humid air is less dense than dry air, simply because a water molecule is less massive than an air (mostly nitrogen) molecule. For those of you who like numbers, the gram-molecular-weight is 18 for water and 28 for nitrogen. The fact that humid air "feels heavy" simply reflects that one's perspiration is more likely to cling to the body when the humidity is high rather than evaporate.

Actually, the effect of humidity is not very large. Using my "trajectory calculator", the effect of varying the relative humidity at 700 from 0% to 100% is only about 2 ft on a 400-foot drive.

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