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The Physics of Baseball

Many people might think that swinging the bat straight through the ball would be enough to hit the ball a decent distance off the bat. There’s many more mechanics involved in the swinging process. Muscle has only a small part to play in the swinging a bat for power. There are two types of mechanics involved while swinging a bat, Linear and Rotational. Rotational mechanics are the dominant source of power in the swing. Out of the rotational mechanics come the two forces that help generate the speed and power of the swing, torque and the other comes from the energy of rotation. Speed from the energy of rotation comes from the path that your hands follow as you swing the bat. The speed generated by the circular rotation from your hands is like a ball at the end of a string, as long as your hands are moving in a circle then the ball continues to accelerate in a circle. So the bat will also move in at an increasing speed as long as your hands are following a circular path as you swing. Any foward movement of the hands or body in a straight line won’t add to the overall bat speed.

Torque is another key ingredient to a good power hitter, or even a good hitter. Torque is the result of two forces being applied to an object in opposite directions. In this case the two forces are being applied from the hands and wrists onto the bat. As you start your swing, instead of moving your hands directly at the ball, you want your hands to start a rotation. The top hand begins to move backwards while the lead arm drives the end of the bat towards the ball. The torque invloved is created around the point of the bat that lies between your hands. This torque greatly accelerates the head of the bat which will have act with a greater force when (or if ) it comes into contact with the ball.

A good batter will use almost all of these rotational and torque energies either before or durning contact with the ball. After contact your body is relaxed and its remaining motion is smooth, this extra motion is caused by the momentum of the bat pulling the arms up and through.Your follow through is also very important, even though the ball has already been hit it is ideal that you complete your swing so that you’re not thrown off balance by that extra momentum when you start to run.

So just remember these three things: while swinging keep hands moving in a circular motion. Remember to rotate your wrist as you swing. And always follow through.

The most noticable difference between a wood or metal bat is the sounds that each create when struck by the ball. I’m quite partial to the sound of a wood bat myself. These differences occur because of the different vibrations that occur in each material. A wood bat has fewer vibration waves than a metal one. This gives the metal bat a greater ‘sweet spot,’ but it also causes a greater sting if you miss that sweet spot. So what would be a give and take for the usage of metal bats have been changed thanks to newer technology. New metal bats have certain qualities that help dampen the sting from a miss-hit ball.

The ‘ping’ sound made from a metal bat has also been a sign of the “trampoline effect.” This effect is thought to allow an aluminum bat to ‘bounce’ the ball further and quicker off the bat. When compared to a wooden bat, there is little difference if both bats hit the ball at their sweet spots. The “effect” from metal bat comes into play when you miss the sweet spot. When you’re off a little with a wooden bat, the bat takes away from the balls kinetic energy resulting in a weaker hit. With a metal bat the bending vibrations still take away from the energy but the cylnder vibrations return that enery back to the ball. There are times when the rebounded energy can be greater than the energy originally taken away from the ball, causeing the ball to fly off the bat much quicker than the pitcher had delivered it. Which raises many safety issues as to whether or not metal bats should be allowed to be used in lower level baseball leagues.

What is the “Sweet Spot”?

The “sweet spot” is that area of the bat where you get the most ‘pop’ out of the bat. It is the ideal place at which to hit the ball for distance. On most bats the sweet spot is found about 17 cm from the end of its barrel. Every hitter can feel when you have hit the sweet spot or not, if you swing, and connect and you dont really feel a thing then its a good bet that you hit at the center of the sweet spot. If your hands sting after you hit the ball, then you missed the sweet spot, and there are times when you really wished you hit that “spot.”

The sweet spot exists due to vibrations occuring in the bat. You become quite aware of these vibrations if you hit the ball off the end of the bat or too close to the handle. Actually the sweet spot exists from the lack of vibartions that occur at that spot. When a bat is swung it is bent enough to excite two different frequencies of vibration. These vibrations create two seperate nodes towards the end of the bat. A node is a point where the a vibrations amplitude equals zero, basically there’s no vibrations at this point. The area between the two nodes in a bat is the sweet spot.

If you hit the ball at a place too far away from the node than alot of energy is transfered from the ball and through the bat exciting the vibrations even further. As you see on the diagram above the vibrations get worse as you move towards the handle of the bat. When the bat is struck between the nodes than little energy is transfered into the bat’s vibrations. Which allows the ball to move from the bat with a greater speed, its not enough to hit a home run every time but it does feel much better.

How to Find the Sweet Spot

To find the sweet spot in a bat, all you need is a hammer, bat, and a friend may be helpful for an extra set of hands. Have your friend hold the bat lightly from the knob of the handle on the bat. Start tapping with the hammer from the barrel of the bat. Your friend, or however is holding the bat, will be able to feel the vibrations as you strike the bat, when you hit the bat and no, or little, vibrations are felt then its a good bet you have found the ‘sweet spot’. You can also tell by the sound that the bat will make when its struck at its node.

The Target

(or What’s inside a Baseball)

The ball, an ever elusive target for hitters. The best hitter in the world had only hit the ball 4 out of every 10 times, a good hitter barely does it 3 for each 10 times at bat. The only difference in todays game is that balls are flying further then in the past. The baseball has changed little over the years on the outside, but on the inside they have been remade several times over the decades. They have been made so that they fly further. The outside dimensions and materials are the same as they were since 1872, 5 ounces and 9 inches in circumference, with a skin of leather and exactly 108 stiches. But the insides have changed dramatically. The basic outline of a ball is the same beneath the leather: rubber cement, four windings of yarn, the first three of wool one of cotton and the final rubber core. Balls used to be made of wool yarn underneath the cover, while newer balls are being made with more and more synthetic fibers. The old wool absorbed moisture very easily, this added wetness can deaden the ball by relaxing the tension and reducing the elasticity of the ball. New balls dont have this problem with the fibers that are being put into balls now.

The core of baseballs are made of compressed rubber. These cores have also become more elastic over the years. Balls that were collected from the early 1970s were tested against newer balls from late 1990s. The older balls only bounced 65 inches, while the newer balls bounced 82 inches. Even with the wear of age this is a remarkeable change in the amount these ball have increased in their bouncyness.

Baseballs have become a little friendlier for batters over the years. But only as far as distance goes, it’s still just as hard to get the bat on the ball as it was over thirty years ago.

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