Physics of Baseball
...rough many states and Canada. Physics has a lot to do with playing the game of baseball. Hitting and fielding the baseball is mostly physics. When a baseball is hit straight towards an outfielder he cannot judge the angle of ascent or the distance the ball will travel quickly. Then if he waits until the trajectory is clearly visible, he has waited too long and will not be able to catch ball that could have been a ball that was once catchable. If starts quickly, and misjudges the ball like if his first step is wrong like in for a deep fly or back for a shallow fly, the time it takes to turn around reduces his range and he will again miss a once catchable ball. To help his judgment, an experienced outfielder will listen to the sound of the bat hitting the ball. If there is a “crack” heard he runs back and if he hears a “clunk” he runs in. To consider the fielder's problem, you need to ask "can he get to the ball in time?" To answer the question you must look at the running speeds of ball players. Figure 2 shows the 1998 world records for different sprint distances. You can summarize the results by noticing that it takes a runner 1.25 seconds to get started and then runs at a speed of around 38 feet per second. These are all world class sprinters which run straight and have the required equipment so they can run at these speeds. A baseball player, who does not run out of blocks, and not knowing where he is going to go prior to the hit surely cannot start as fast as the sprinter. It is estimated by Robert Adair that “the player needs an extra half-second. And running with baseball spikes on grass, in a baseball uniform, carrying a glove, and glancing over his shoulder at the ball as he runs, I take 30 feet per second as the running speed of a fast outfielder going after a ball.” Figure 3 shows the distance the ball player runs with a function of time as the model, together with the distance the sprinter in his track suit, track shoes, and the remainder of his equipment, running 38 feet per second, would say he has the same start delay as the baseball player. With this information, in Figure 4, there is a drawing of the distance, 100 feet that an outfielder, playing center field, can cover the typical flight time for a fly ball in five seconds, if he ran in a straight line. There is one problem with this though. It is that the fielder would start as the batter swung the bat, not at the crack of the bat which would take about .3 seconds to realize and then get going. So there was .3 seconds added for this. The curved lines show actual paths used in catching short and long distance balls hit off to the side. With the 1.75 seconds starting time, there was the 0.3 seconds added. He can start immediately to his right and run in that direction for the one or more seconds that gives him enough information to see if the ball will land long or short. With the delay in starting and the extra distance he must run this reduces his range to about 85 feet in the 5 seconds after the bat hit the ball. A regular baseball bat is about five times heavier than a regulation baseball. If the batter swings the bat with a speed that is close to the speed of the pitch, the bat will have about five times more momentum than the ball at the time of collision. Most of the collision energy will be transferred to the ball and the momentum of the bat will barely be affected. For example look at the difference between gently tossing a baseball at a wall and throwing the baseball with force. The harder you throw the ball at the wall, the farther it will go back on rebound. Therefore the faster the pitch is the further the baseball will be hit. There is also a lot of physics involved in pitching the baseball too. As the pitcher releases the ball, the grip will put a spin on the baseball. As the ball moves through air, it encounters a force called drag. Drag is another name for air friction. If a baseball is not spinning, air friction will only slow the ball down. However, at least for a baseball, when the baseball is spinning, the force of drag will be different at all points. The force of drag is smaller on one side of the baseball. This imbalance of force causes the baseball to curve. Another factor which helps a baseball to curve is roughness. A baseball cannot be considered a smooth because they have stitches; in fact, there are 108 of them on every baseball. These stitches contribute to the imbalance of the drag. If the baseball was "perfectly" smooth, there would not be any of the special pitches of baseball, like the curveball or slider. They would not be possible because there would not be enough drag to throw them. But because of the stitches, the spin of these pitches will cause them to curve. Some people say that fastballs spin and they do not curve! Many baseball players know that fastballs do curve. In fact, a 90 mile per hour fastball will jump as much as 4 inches There are physics involved in the spin of the baseball also. The axis of spin on a ball thrown by a right-handed pitcher will go upwards from left to right; overhand fastballs will backspin, while other pitches do not. A southpaw (or left handed pitcher) will go down from left to right as seen by the batter. This means that when the batter and the pitcher are favoring the same hand, a fastball will angle high and inside, and other pitches will angle low and outside, when aimed at the same place. A knuckleball is thrown with little to no spin, which is unlike any other pitch. There is about a half rotation between the pitcher and the batter. Many pitchers say that if a knuckleball is thrown correctly it will have one full rotation before getting to the catcher. There are many other pitchers who rely on a little more spin on the baseball, bec...