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Physics of Baseball     |     home
Physics of Hitting a Baseball   |   How Do Pitchers Throw Different Types of Pitches?   |   Reaction Time   |   After Hitting the Baseball   |   "Sweet Spot"   |   Physics of Throwing a Baseball   |   Conclusion   |   Bibliography   |   Interactive Baseball Games
Physics of Hitting a Baseball
        In the game of baseball there are many features that play a roll in how the game is played.  When out on the field most people, if asked, would not be able to find the relationship between physics and baseball.  However, there are many aspects to physics that are involved in the sport.  Physics is mostly involved in the hitting process. A moving ball travels towards a moving bat.  A physics term Velocity, which is a vector quantity that includes the speed and the direction of the object, is highly involved in baseball.  There are many aspects of velocity such as “the velocity of the bat, the velocity of the ball, the masses of the ball and the bat” (Sakamoto).  All of these individual physics terms can help a baseball player develop the skill to know how to play the game.    One example is based on the velocity of the bat hitting the ball a baseball player can determine how far a ball will travel after it has been hit.  An important term to know when is “coefficient of restitution. This is the physics term for what happens to the ball and bat before and after contact is made” (Sakamoto).  It mainly focuses on the amount of the percentage that the ball retains its energy.  In explaining this term an example of dropping a ball is given.  The measure of the drop, for this example, bounces up to exactly the same height. The readings of this sort of outcome would be 1, or 100%. The average is around .5, or 50%. Knowing how to measure coefficient restitution is vital in hitting a baseball because “the higher the number, the more energy from the ball and bat is saved and transferred to the ball on impact”(Sakamoto) and if the number is lower the ball does not have as much as the bat.  
     To further utilize the coefficient restitution it is also important to understand the sweet spot.  The sweet spot is the place on the bat where “energy is transferred with the least amount of energy lost. Anywhere outside of the sweet spot, more and more energy is lost and absorbed by the bat” (Sakamoto).  When playing baseball it is important to try to hit the ball on the sweet spot. Doing so will cause the ball to go farther.  It is noted that “more energy is conserved and transferred to the ball, and the ball travels faster and farther” (Sakamoto).  A simple way to find the bat's sweet spot is to first hold the bat in one hand several inches from the knob, second take a ball and bounce it up the barrel of the bat and third when you get to the point where you can not feel the ball hit the bat you have located the sweet spot.
     While the kinetic energy transferred from the bat to the ball accounts for some of the energy of the ball, it does not account for everything. Momentum is what accounts for the transfer of energy.  Scientists describe momentum as being a “quantity of motion" or in mathematical terms p (momentum) = mass * velocity” (Physics of Baseball). Physics proves to us that Newton's 2nd law: F=ma (Force equals mass times acceleration) also plays a major roll in playing the game of baseball.  The acceleration is dv/dt, which is the change in the velocity (dv) divided by the change in time (dt). “The change velocity (dv) is the difference between the current value and the last value of the velocity” (Physics of Baseball).  In this case, dv=vf-vi, or, the change in velocity equals the final velocity minus the initial velocity.
Also another thing to take into consideration is the size of the bat used while playing the game. A ball will travel farther when a heavier bat is used. However, this is
“only true if the ball is hit with the same velocity of a bat swing”(Sakamoto). Because of this known fact some baseball players who want to gain more speed use lighter bats. Also the way that a ball is pitched will also effect how the game is played.  If the ball is pitched slower, “to hit the ball as far as if the ball was pitched at a faster velocity, you would have to compensate and hit the ball harder” (Sakamoto).  Another aspect that must be noted is the angle the ball and bat meet.  For a better hit the ball should hit the bat at a forty five (45) degree angle. Hitting the ball on a straight line will send the ball traveling back in a straight line.  This is called a line-drive.  If the ball is hit under the bat it will be hit at a greater angle.  This is called a pop up. Finally if the ball is hit on top by the bat, it will be a grounder.