Hitting a baseball is one of the most impressive feats in all of sports. It is something that is very difficult to do, as the pitcher and batter stand merely 60.5 feet apart (which is likely shortened by the pitcher’s stride) while the ball can cross the plate at speeds upward of 100 miles per hour! Both hitting and pitching have many similar lower body movements in order to exert forces on the ball. I am going to attempt to explain how a baseball swing generates power and the physics behind getting a hit, as well as some pitching mechanics that pitchers can use to make their pitches harder to hit.
First, I want to explain the movement of the baseball which will make it easier to understand its movement through the air. An advanced statistic that many scouts are using to evaluate the potential effectiveness of a pitch are its revolutions per minute (RPM), or the amount of rotations a ball would complete in a minute. One of the game’s best pitchers, like Corbin Burns of the Milwaukee Brewers, has a spin rate of almost 2700 RPM on his fastball. On a four-seam fastball, the backspin that the ball spins with after the throw generates a force underneath the baseball perpendicular to the ground that keeps it in the air until it crosses the plate. This force generated by the spin of the baseball that keeps it airborne helps to resist the force of gravity, which pulls the ball downwards towards the Earth. This is an important concept for the batter, as well, because if they are able to keep a well-struck ball in the air for a longer period of time, it has a possibility of going over the fence for a home run.
When a pitcher is on the pitcher’s mound they are elevated above the surface that the batter stands on. Because they are throwing the ball on a downward slope, and although the air pressure resulting from the spin of the ball keeps it airborne, the force of gravity still contributes to the velocity of the pitch. The pitcher can maximize this velocity by throwing the ball at the highest point they can reach. When starting a wind-up, the pitcher moves backwards to shift their weight back onto their back leg before rotating their hips. As the pitcher comes forward with the delivery of the ball, they push off of the mound and extend their arm to the highest possible point. This maximizes the torque arm which creates a greater angular acceleration, and in turn a greater tangential velocity (show relationship). Another component of pitching that allows the pitcher to challenge the batter is to close off the distance to the plate during their delivery. Despite the distance of 60.5 feet from pitcher’s mound to home plate, pitchers who can explode off the mound shorten this distance from their release point. For example, when I pitch, I am able to release the ball almost 7 feet closer to home plate than the pitcher’s mound. This is only able to be accomplished by extending my body, which not only increases velocity, but also shortens the batter’s reaction time.
It seems miraculous that although there are pitchers who can throw the ball 100 miles per hour, there are players like Giancarlo Stanton of the Yankees who can hit pitches as hard as 119 miles per hour. Although a pitch has a huge amount of momentum as it approaches the plate, the swing of the batter has lots of momentum itself. Also due to the rigid nature and curved barrel, a harder pitch travels harder off of the bat. This is because although a small amount of momentum is lost, the bat provides the ball with momentum in the opposite direction that exceeds the ball after the throw! It is the rotation of the batter and their shift of weight that provides this enormous impulse.
When swinging at a fastball, the batter’s quality of contact with the ball determines the spin of the ball, which can lead to many different outcomes. If a right handed batter is late on an inside pitch and hits it off the handle of the bat, the ball rotates downwards and often does not go far. This is because most of the energy of the ball is transferred into vibrational energy that jolts through the handle, giving a painful sting to the hands of the batter, instead of being transferred into the barrel through the swing and propelled over the left field fence. The barrel is the sweet spot of the bat where most of the energy is transferred to the baseball, and not into vibrational energy like the far end or handle of the bat.
All in all, baseball is a pretty hard sport to play, yet alone be good at. Both pitchers and hitters need to know how to maneuver parts of their body in ways that maximize the speed in which the ball moves, and need to have pinpoint precision and reactions. This has just been a brief look into some of the physics concepts that players use (whether they are aware of them or not), and I personally think that breaking these down will enable me to better understand the sport and use physics to my advantage on the field!