Ask Mrs. Benson!

Welcome to our regular feature here on It's Mets for Me! Mrs. Benson is here to take your hardball questions, so line right up and fire away!





Q: How do you account for Tom Glavine's recent sucess?
--Bill, Flushing, NY

A: Thanks for your question, William. I attribute Glavine's improved pitching to the way he has mixed a curveball in to his repertoire. To be precise, when I say curveball, this means that the spinning ball creates drag. An air flow is created on one side ofthe ball that is in the same direction as the air that is rushing past theball in its flight. On the opposite side of the ball, the air flow is reversed, and runs against the air rushing past. This has the effect of slowing down the overall air flow on that side of the ball, while on theother side, where the flow is in the same direction, it has the effect of speeding it up. Magnus Force is an important concept in this discussion, but the Bernoulli Effect comes into play here as well: the greater the velocity of air, the less pressure it will exert. So the side of the ball where the velocity of the air has been reduced will have a greaterpressure exerted on it...and hence, the ball will be pushed to the other side.

Newton actually recognized the effect earlier than Magnus did. Newton saw that a tennis ball "struck with an oblique racket" would curve. Bernoulli also determined that as speed of a fluid is increased, its pressure decreases as stated in his famous Bernoulli's Principle.

Now, Magnus Force is similar to Bernoulli's Principle, but not quite (or we would be calling it Bernoulli's Principle). For a spinning ball, the stitches on the ball will cause pressure on one side to be less than on its opposite side. This will force the ball to move faster on one side than the other and will force the ball to "curve." This is the Magnus Effect.

How much will a baseball curve?. The equation is as follows:
FMagnus Force = KwVCv
where:
FMagnus Force is the Magnus Force
K is the Magnus Coefficient
w is the spin frequency measured in rpm
V is the velocity of the ball in mph
Cv is the drag coefficient

Well, William, I think that explains it! Thanks for your question.
AB