The most interesting example of ball movement in baseball is the curveball. The secret to understanding a curveball is the speed of the air moving past the ball's surface. As the ball spins, its top surface moves in the same direction in which the air moves. At the bottom of the ball, the ball's surface and the air move in opposite directions. So the velocity of the air relative to that of the ball's surface is larger on the bottom of the ball. The higher velocity difference puts more stress on the air flowing around the bottom of the ball. That stress makes air flowing around the ball "break away" from the ball's surface sooner. On the other hand, the air at the top of the spinning ball, subject to less stress due to the lower velocity difference, can "hang onto" the ball's surface longer before breaking away. As a result, the air flowing over the top of the ball leaves it in a direction pointed a little bit downward rather than straight back. So, as the spinning ball throws the air down, the air pushes the ball up in response. A ball thrown with backspin will therefore get a little bit of lift. A major league curveball can veer as much as 171/2 inches from a straight line by the time it crosses the plate. Over the course of a pitch, the deflection from a straight line increases with distance from the pitcher. So curveballs do most of their curving in the last quarter of their trip. Considering that it takes less time for the ball to travel those last 15 feet (about 1/6 of a second) than it takes for the batter to swing the bat (about 1/5 of a second), hitters must begin their swings before the ball has started to show much curve. This, obviously, makes curveballs very hard to hit.
The most important pitch in baseball is the fastball. There are many different variations of the fastball (four-seam and split-finger fastball). The four-seam fastball or the rising fastball is thrown straight and hard with a lot of backspin. Your index and middle finger are positioned across two seams, so when thrown four seams rotate in the backspin. A good rising fastball thrown hard enough with enough backspin can rise four inches from the lowest point of trajectory to the catcher's mitt. On the other hand, the splitfinger is thrown with the fingers split apart, like a V, and directed along the seams of the ball. With this grip, the airflow sees only two seams, so the average surface is much smoother, and a greater air resistance is felt, resulting in a slightly slower pitch. The effect of splitting the fingers is to allow the ball to "slip" out between them and approach home plate with less backspin. This eliminates the "hop" of the rising fastball, allowing the ball to drop as much as 16 inches, and is the essence of the splitter.
One important difference between a fastball, a curveball, a slider, and a screwball is the direction in which the ball spins. (Other important factors are the speed of the pitch and rate of spin.) Generally, a ball thrown with a spin will curve in the same direction that the front of the ball (home plate side, when pitched) turns. If the ball is spinning from top to bottom (topspin), it will tend to nosedive into the dirt. If it's spinning from left to right, the pitch will break toward third base. The faster the rate of spin, the more the ball's path curves.
The Spitball and other Illegal Pitches
The spitball is thrown in one of two ways; initially it was thrown by applying a foreign substance, such as saliva or petroleum jelly to the ball preferentially to one side. For many years, this was legal in the game of baseball, but later, the spitball was forbidden. Some pitchers threw it anyway, while others found it easier to achieve the same effect by scuffing one side of the ball preferentially. Pitchers have been known to use such objects as wedding rings, nail files, thumbtacks, bent eyelets on their gloves, pine tar, or perspiration to disfigure the ball with the intent of changing its trajectory. Anything that damages the surface of the ball is illegal, according to the official rules of baseball. Despite the rule, scuffing has, historically, taken place and probably still does. The strategy has two effects. First, it allows the pitcher to throw the ball just like he'd throw a fastball, resulting in speeds much higher than those of a knuckleball or a curve. The difference between the fastball and the spit ball, then, is the amazing amount of movement imparted by the "spit" and the ease with which a pitcher can make the ball move either right or left. A knuckleball moves because the surface is asymmetric, resulting in more turbulence in one part of the airflow than in another. Scuffing or spitting on the ball achieves this same effect, only at a much higher speed. The result is a fastball that breaks either like a curveball or like a screwball (a screwball is like a curveball, only it's spun in the opposite direction, so that it will curve away from the pitcher, as opposed to back across his body), depending on the orientation of the scuff with which the pitcher chooses to hold the ball. Clearly, then, the spitball gives its thrower an advantage that is simply not fair, so baseball decided to outlaw it.
The Knuckleball
The knuckle ball is devastating to the batter because of its unpredictable path. It may go left by 12" and then to the right by the same amount all in the same pitch in an unpredictable way. Even catchers of knuckle balls have trouble putting their mitt in the right place and they knew that a knuckle ball was coming. The ideal knuckle ball is thrown with hardly any spin. Because a baseball has seams, the ball thrown with no spin will present different seam patterns to the air which pumps air to different sides of the ball. If the ball rotates by 1/4 turn, the seams are different and air is pumped to a different direction. The unpredictable forces and hence accelerations causes displacements of the ball away from the parabolic gravitational arc. Since the knuckle ball has such an unpredictable flight, the pitcher can throw balls with very small velocities with a good chance that the ball cannot be hit. By pitching with vastly different velocities, the timing of the swing is affected to further trouble the would be hitter. Good knuckleball pitchers are rare. It seems that the technique for throwing a ball such that it rotates only 1 or 1/2 times on its flight is very difficult to develop.
The Physics of Hitting
Anticipation comes into play when hitting. Watching the pitcher and how he throws the ball is a big part of hitting. Since different spins on the ball cause it to drop or curve due to friction between the laces and the air, the batter needs to pay close attention. Watching the spin determines where and when the batter will swing. He needs to project the speed of the ball and where it will cross the plate. The angle that which the ball hits the bat will determine its angle of projection. When starting to swing, great acceleration takes place and momentum is also being increased. The power of the batters swing has to do with how much time took place between the start and finish of the swing and how much work was put into the swing. Newton's third law; For every action there is an opposite and equal reaction. This determines how far the ball is hit.
The hands play an important role during the actual swing prior to the actual contact, as they help transfer energy in the muscles of the body to the baseball bat. This muscle power propels the bat to the high velocity needed to transfer a lot of momentum to the ball and send it on its way. But during the bat-ball contact time, the grip does nothing to affect the ball's final velocity or trajectory. The collision between bat and ball creates a vibrational wave in the bat. The wave originates at the collision point and ripples down to the hand. The wave itself, since it absorbs energy from the baseball, can affect the exit speed of the ball. But by the time the wave hits the hand, the ball is already separated from the bat, and there's nothing that the hands can do to alter this vibrational wave, assuming of course that the impact occurs in the barrel of the bat, far from the hands.
A main concern when hitting is making contact closest to the "sweet spot" of the bat as possible. The baseball bat really has three sweet spots. The center most is called the center of percussion (COP). The COP is the term used for the spot on the bat that would cause the least amount of shock to travel to your hands when batting. If you hit a baseball closer to the bat's handle than to the center of percussion, you'll feel a slight force pushing the handle back into the palm of your top hand. If you hit the ball farther out than the COP, you'll feel a slight push on your fingers in the opposite direction, trying to open up your grip. But if you hit the ball right on the COP, you won't feel any force on the handle.
The batter exerts some 6000-8000 pounds of force on the ball. This force is required to change a 5 1/8th ounce ball from a speed of 90 mph to a speed of 110 mph, this distorts the baseball to half its original diameter and the bat is compressed one fiftieth of its size. Good news for batters, the "muzzle velocity" of a pitched baseball slows down about 1 mph every 7 feet after it leaves the pitcher's hand, that's a loss of roughly 8 mph by the time it crosses the plate. Bad news for batters, if you swing 1/100th of a second too soon a ball will go foul down the left field side (right handed batter), 1/100th of a second too late and it's foul in the right field seats (and the decision to swing has to happen within .04 seconds).
As you and I have found out, a great deal of information can be understood on the basis of the physics' principals. After looking at the physics for pitching and hitting, I understand how and why things happen in the game of baseball. I have found new and interesting facts that will be useful to me, as a pitcher, in my upcoming baseball season. At the bottom of this paragraph I have listed more attention-grabbing facts that I found fascinating.
Did You Know ?
*To hit a ball for maximum distance, the trajectory off the bat should have a 35-degree angle.
*An average head wind (10 miles per hour) can turn a 400-foot home run into a 370-foot out.
*A 400-foot home run will go about 6 feet farther for every inch reduction on the barometer.
*The collision of a ball on the bat lasts only about 1/100th of a second.
*A batted ball should be able to travel no farther than 545 feet (excluding meteorologically freaky conditions).
*There is no such thing (except in softball) as a rising fastball!
