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The Perfect Pitch: The Physics Behind the Knuckleball

Author: Ted Isidor

Editors: Eric Lin and Aanya Ram

Artist: Esther Chen

During this past summer, I faced an annoying dilemma that every sports fan hates: the end of a season. I watch fútbol leagues such as the Premier League, but after a long and heartbreaking season as a Liverpool fan, I was bored out of my mind when I realized that there would be no more Prems for two months. Out of desperation, I stepped out of my comfort zone and began watching different kinds of sports, the first of which was baseball since it was the only sport that still had its season going on. It turned out to be one of the best decisions ever. At first, I thought baseball wasn’t that entertaining of a sport because they only hit a ball with a bat, but after watching a couple of MLB innings, I realized I couldn’t be more wrong. To not only throw but also hit a baseball traveling at speeds over 80 miles per hour, baseball players have to train insane amounts and learn some tricks to win. One of these tricks I want to bring to your attention is the knuckleball pitch, so rare that, out of the hundreds of pitchers in the league at the moment, only a handful can throw this pitch.

A knuckleball pitch is pretty much when the pitcher throws the baseball so that it has nearly zero spins as it travels to the mound. To put this in perspective, a normal baseball rotates in mid-air after being thrown. The magnitude of the rotation has a big effect on the direction the object takes, how the air around the ball is being manipulated, etc. From a physics perspective, three main forces are acting on a baseball as it travels through the air: gravity, drag force, air pressure, and Magnus force. When it comes to knuckleball, however, air pressure and drag play a huge role in causing the wiggly phenomenon. An object traveling through a medium (like a baseball traveling through the air) has a boundary layer, which is a thin layer of air that comes into contact with the object. Initially, as the ball travels, it is doing so smoothly (a phenomenon called laminar flow) until some kind of disturbance ruins the good moment (like when you are having a great dream and then your alarm goes off). The new state the object is in is called turbulent flow. Due to this transition from laminar to turbulent flow, the baseball undergoes a “drag crisis,” causing the erratic movement a knuckleball is known for (Inverse).

By minimizing the amount of spin on a baseball as it travels, the ball begins to dance in the air, wiggling as it travels (MLB). This leads to a harder time for batters to try and determine where the balls are going to go so that they can hit them. Doesn't this sound like the ideal kind of pitch? One that is so unpredictable that both the pitcher, batter, and umpire have no real clue what might unfold. If this were to be true, nearly every pitcher would be training overtime for this pitch, but one of the main reasons why knuckleball pitchers are scarce, according to the MLB itself, is that “the obvious downside to the knuckleball is that if it isn't "dancing" or moving, it becomes very easy to hit because of the slow speed of the pitch.” Alas, the magnum opus of baseball pitches has its flaws. The few MLB pitchers that have or are currently able to do a knuckleball do it exclusively, as they need to "'have a feel' "for the pitch that requires using it all the time." (NPR).

The knuckleball is just one of the many fascinating things about baseball. This sport has many amazing plays, awesome traditions, and dedicated fans that would catch the attention of science, history, and sports enthusiasts alike. Whenever convenient, watch a game of baseball, who knows it might be an out-of-the-park experience!!

 

Citations:

Cimbala, J. M. Drag on Spheres. 2012,

www.me.psu.edu/cimbala/me325web_Spring_2012/Labs/Drag/intro.pdf.

“Knuckleball (KN) | Glossary | MLB.com.” MLB.com, 2023, www.mlb.com/glossary/pitch-

types/knuckleball. Accessed 1 Oct. 2023.

Memmott, Mark. “The Knuckleball Can Devastate, so Why Don’t All Pitchers Throw It?”

NPR, 14 Aug. 2013, www.npr.org/sections/thetwo-way/2013/08/13/211667018/the-

knuckleball-can-devastate-so-why-dont-all-pitchers-throw-it. Accessed 1 Oct. 2023.

“The Physics of the Knuckleball.” Inverse, 19 Aug. 2016, www.inverse.com/article/19897-

2016-rio-olympics-physics-knuckleball. Accessed 1 Oct. 2023.

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