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Benefits of Rotational Hitting

Posted by: Mike Myers () on Tue Sep 17 14:29:59 2002


I would be happy to explain the benefits of rotational hitting.

Consider an object’s momentum is its mass x its velocity. Energy delivered by the body during swing will cause momentum in the bat. Since the body is continuously supplying energy throughout the swing, bat momentum is increasing until time of impact.

Conservation of momentum states that net momentum of a system before a collision is identical to net momentum of a system after a collision. Thus, if you have 1 billiard ball travelling toward another billiard ball, each will have its own mass and velocity. Net momentum before the collision is (m1v1 + m2v2). After impact, the masses are unchanged, however, final velocities will differ as the balls separate. Net momentum is now (m1v1f + m2v2f). Conservation of mometum states: m1v1 + m2v2 = m1v1f + m2v2f.

In baseball, just before the bat collides with the ball, system momentum is: mbat x vbat + mball x vball. Just after the collision, the bat will recoil, and the ball will fly. Final system momentum is: mbat x vbatf + mball x vballf.

Equating initial and final state momentum:

mbat x vbat + mball x vball = mbat x vbatf + mball x vballf.

Mass of bat and ball do not change – only their relative velocities. Now, the official 2000 rules (www.mlb.com) state the ball must weigh between 5 and 5.25 ounces. There is no regulation on the mass of the bat, only a length and diameter restriction. Let us assume the bat is a typical 30 oz. Then mbat is approx 6 x mball. Therefore:

6 x mball x vbat + mball x vball = 6 x mball x vbatf + mball x vballf
or mball (6vbat + vball) = mball (6vbatf + vballf)
6vbat + vball = 6vbatf + vballf

With all constants accounted for, the only factors which remain to affect ball launch speed after contact, are pitch speed (vball) and batspeed (vbat) just before contact. Also, one can see bat speed has a 6 x larger factor on system momentum than ball speed, so developing high bat speed is critical in developing home run power. If you increase your bat speed by just 5mph at contact, this will have the same effect as contacting a pitch thrown 30mph harder.

The human body can produce bat motion with a variety of methods. The question is, with fixed energy, how is this motion most efficient to produce maximum batspeed? The answer is to realize we are only concerned with maximizing speed in the part of the bat which contacts the ball (ideally, the sweet spot).

Thus, consider the bat to contain many small sections, with a small mass in each section. Each with separate motion characteristics. Now, each small bat section will have its own ((small m) x v) characteristic at every instance in time. Since we want the sweet spot of the bat to have highest possible velocity, then we must realize, for a bat with fixed energy input, higher speed in some bat parts, must mean lower speed in other bat parts.

What is the only possible bat motion which sacrifices speed maximally in certain parts, so as to maximize speed at the sweet spot? The answer is: rotation about the knob. Actually, the far end of the bat will be travelling even faster than the sweet spot, but we cannot optimize our mechanic any further since the bat is a rigid body which must maintain its shape throughout movement.

Now, what if the human body cannot harness all its energy into keeping the knob on a stationary axis and accelerating the bat head maximally? We must re-examine the optimal energy-to-bat transfer mechanic (rotation about knob) to consider the next best alternative. The body has long and massive limbs whose chief power sources operate at a distance, causing arm and leg rotation about joints far from the bat. We realize the human body itself, should ideally rotate as well to produce maximal torque (force of rotation) on the hands and consequently, the bat. Thus, the bats’ ideal axis of rotation to produce maximal bat speed, should actually lie about the center of the rotating human body.


To All,
> > > > > > > > > >
> > > > > > > > > > Hitting is a very standard activity. There are differences in the size of balls (softball and baseball), distances vary from game to game. Bats are different but within a very narrow rang. The material the bat is made of makes little difference in mechanics. We have a round ball and bats that are the same shape with insignificant differences in size when it comes to mechanics.
> > > > > > > > > >
> > > > > > > > > > So, we have a very standardized universe of equipment. Hitters are all basically the same shape. Everyone's arms are in the same place as are their head and legs. They all operate the same. There are differences in size but the fundamental structure is the same for all hitters.
> > > > > > > > > >
> > > > > > > > > > The idea is to use the bat to hit the ball as hard as possible. Because of the physical characteristics of the bat and ball, hitting it hard requires more then a hard/fast swing. Maximum force comes from a balance between control and power. Hitting the ball in the middle is just as or all most important has the power from the bat speed.
> > > > > > > > > >
> > > > > > > > > > The act of hitting a ball is a physical act which is governed by the laws of physics. There are almost no situations is natural law where there are two equally best ways to do something. Because all the factors (equipment and the body) are almost identical, there is only one method for apply maximum force to a sphere with a bat. The differences that do exist are of no relevance to the basic mechanics of hitting the ball. The size of the batter or the bat the speed and size of the ball, etc, etc, etc, will have an impact on the results. But there is only one method of swinging that will give the control to hit the ball in the best place with a bat speed that will produce maximum force to the ball.
> > > > > > > > > >
> > > > > > > > > > I make this statement not because I intend to say what the best method is. But this issue is fundamental to the entire discussion. If you cannot agreee that there is a "one best method" then anything goes and all ideas are equal. This is unscientific and illogical.
> > > > > > > > > >
> > > > > > > > > > S. Procito
> > > > > > > > >
> > > > > > > > > S. Procito,
> > > > > > > > >
> > > > > > > > > Your statement "There are almost no situations in natural law where there are two equally best ways to do something" is false.
> > > > > > > > >
> > > > > > > > > Consider projectiles in free-fall physics: "What is the optimal angle to launch an object (of mass m and initial velocity vi) such that the final velocity vf (at time of ground impact) is maximized.
> > > > > > > > >
> > > > > > > > > This:
> > > > > > > > > 1. Is a natural situation.
> > > > > > > > > 2. Equates to EVERY angle yields maximum results. Why? Because energy of the system is FIXED. Regardless of launch angle, the system must conserve energy until the object impacts the ground. When the ball impacts ground all energy is kinetic, as it was when the object was launched, so initial and final speeds are equal.
> > > > > > > > >
> > > > > > > > > You conclude that since mass of bat, ball, and person are simple variables, they only affect result, not the optimal method. This is not necessarily the case. Basically, any equation model (polynomial incorporating all of the variables you introduce) can have multiple maxima, depending on behaviour. In fact, if you take the derivative of your model, and set it to zero, ignoring minima, you will see exactly how many equally optimal possibilities exist.
> > > > > > > > >
> > > > > > > > > Since, in baseball, you are looking at a transform of fixed energy into optimal batspeed, it is not necessarily clear that one and only one mechanic exists to optimize this result. Humans can move many body parts in different angles and sequences such that net batspeed is no different after time t.
> > > > > > > > >
> > > > > > > > > The fact that this is the case would not discourage me from learning a variety of hitting tactics of reasonable logic.
> > > > > > > > >
> > > > > > > > > Regards,
> > > > > > > > > Mike.
> > > > > > > > >
> > > > > > > > >Hey when I was on my sabatikal I lerned a lot of new things.You guys were right on some stuff and wrong on a lot of stuff.I can say unakwivikably theres a right way to hit and a wrong way and maybe just me and a few others really know the master plan.
> > > > > > >
> > > > > > > Thanks for coming back, Joe. I have always learned something new from you and I'm sure I will in the future as well. Welcome back!
> > > > > >
> > > > > > Ah, my imposturator. Very good, you even get the email address now!
> > > > > > Do you also do the JoeA posts you answer?
> > > > >
> > > > > While this is all undeniably funny, I don't think it is subtle enough to be the authentic original Joe A. Or maybe he's just rusty. In any case, I enjoyed it.
> > > > >
> > > > > Mark H.
> > > >
> > > > Mike,
> > > >
> > > > I am confused with two things in your post which distracted me from all that you said.
> > > >
> > > > #1, you said "Consider projectiles in free-fall physics: "What is the optimal angle to launch an object............"." Aren't the terms "free-fall" and the word "launched" contradictory. Something that is "free-falling" is not "launched" Explain.
> > >
> > > No. Free-Falling refers to the fact that the object is subjected only to the force of gravity while it travels - it is not a rocket being continuously propelled, for example. Every object is initially launched before it begins it's state of free-fall. Whether you drop an object, or launch it, the object's initial velocity (energy input) is all that is required to determine the object's final state (position, velocity, and time to reach these states) since gravity is the only force acting on the object as it travels. Consider, if you throw a spear, as soon as the spear leaves your hand, it is falling predictably, and independently, of its horizontal motion. The time for the spear to reach ground, and it's final velocity, is governed mostly by the behaviour of gravity. Wind or air resistance are the only other factors which determine its flight characteristics.
> > > >
> > > > #2. The force applied to a baseball is "ballistic in nature. I don't think the word "launched" is appropriate. But, at the instant after the ball struck it is at optimum speed. Since it is ballistic, the ball instantly starts slowing down when the force (the bat) is removed.
> > > >
> > > > I don't get your reference that > "When the ball impacts ground all energy is kinetic, as it was when the object was launched, so initial and final speeds are equal." Let me ask you this, would you rather catch a struck ball from 3 feet from where it is hit or in the outfield standing over the spot where it will land? Ask any little league third baseman where he would play.
> > >
> > > You must consider an object in free-fall to have independent horizontal and vertical coordinates of behaviour. Of course, due to the effects of air resistance, the ball speed in the horizontal direction will have been slowed considerably by the time it reaches the outfield. However, it is not true to say ball speed is continuosly decreasing after it leaves the bat. Consider a high pop up which lands on second base. If you could position a fielder to catch the ball at the ball's peak height above the pitching mound, who do you think would experience a harder thud in their glove - this fielder, or the second baseman who catches the ball at ground level?
> > >
> > > In my example I was just showing that, ideally, the energy of the ball is fixed (ignoring air resistance) until the ball impacts ground. It may appear when the ball is it at its peak height, that it has lost kinetic energy (energy of movement), however, this energy has only been temporarily transformed to potential energy. When the ball begins falling again, the energy is transformed again to kinetic energy. The ground absorbs ball energy on impact.
> > >
> > > I agree with the concept of determining optimum mechanics for producing the best baseball swing. This does include the rotational concept. However, simply because maximum body rotation is the desirable result, does not indicate the method of producing maximum rotation (ie sequence of leg, hip, shoulder movement) must be unique. I believe certain methods are far more useful and logical than others, but to say there is abolutely only one way to swing to produce optimal batspeed is speculation. S. Procito, however, presented it as established fact. To support his argument he merely indicates mass and shape of bat, ball, and person are known quantities. As I stated, these standards do not indicate transforming fixed body energy into maximum batspeed can be accomplished in one, and only one, swing pattern.
> >
> > Mike-
> > well said and to the point. I agree completely.
> Mike
> I'm with MD, such succinctness and proverb in your writing. Now please, take that comprehensive knowledge and explain pre-impact phenomena to us. Please incorporate all concepts: include kinetics, (on bat) radial force, possible torque. Include energy (if possible). How does consvervation of momentum apply? These are concepts I have read about but do not understand, but after reading your previous post I hope you can simplify them for me. You sure did well in your previous post. Thank you Mike
> x


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