Inertia – Power from the Back of the Bus


Most elementary Science teachers will begin their instruction on the study of inertia with the application of its principle along with a frame of reference relative to the Newtonian laws of motion. Simply stated, inertia is the tendency of a body at rest, or in motion, to remain in that state unless disturbed by an external force. The common imagery used by teachers is that of a bus colliding head-on with an immovable object. If the bus is travelling at a speed of 100 MPH, and the object hit is truly immoveable, then the entire contents (unless securely fastened) at the back of the bus will explode forward at the speed of 100 MPH. Newton’s third law of motion helps to enhance the imagery by understanding that, “every action has an opposite and equal reaction.”

The principles governing the aforementioned laws have their applications in various aspects of our National Pastime. A casual observer would be hard pressed to notice the specific application of Physics in correlation to the areas of fielding and running, although we all know they are there. But with regard to batting and throwing, everyone has at least an inkling of an understanding that proper mechanical application of the subtle laws of physics has afforded certain individuals uncommon advantage over their less astute peers.
Raw strength is usually a great advantage one has over a player with noticeably less power. When both are equally adept in mechanical technique, then the stronger will always have the upper-hand. But if the less strong player has better mechanics, he is usually the more proficient batsman, even with regard to hitting for distance. Look at Joe Morgan, Ted Williams and Stan Musial compared to larger, more muscular players.
There are many facets to consider when establishing the proper mechanics for batting and throwing, but this essay will consider only how the “inertial principle” is applied, relative to the size and strength of individuals throwing and hitting a baseball. The forward movements of the bus and the body are not identical, but their accommodation to the Physics principle is similar enough to be of practical import. To be remembered is the additional fact that if the object struck by the bus is not totally immoveable, the degree to which the impact is defused will determine the actual speed of the objects thrown forward inside the bus ( if not securely fastened).
Newton’s equation, F=ma, is described as, the Force unleashed is equal to the mass (size, weight, and strength) times the speed of acceleration of the moving object. Therefore a bus and a motor-cycle hitting an immoveable object will not have the same force of impact. However, a rider on a motor-cycle and a rider on top of a bus, each travelling at a speed of 100 MPH, and each having a baseball in hand, toss the balls forward at 5 MPH. Both balls would travel at a speed 105 MPH.
So, how does a human-body generate the amount of force that is equal to the body’s mass times acceleration (F=ma) to throw and hit a baseball with maximum power?
In Baseball it is not uncommon to see a “little-guy” throw and hit a baseball as hard as does the “big-guy.” Although the “big-guy” might have more size and weight, he might not generate the same speed of acceleration as the “little-guy.” But in cases where the “big-guy” generates the same, or greater speed, the Force becomes uncontestable, and incomparable (Bo Jackson and Mark McQwire).
Although the speed of a thrown ball is important at all positions on the field, we will place maximum attention on the pitcher. Except for situations when a runner is on base, the pitcher can take his time and build increasing momentum before coming to the point where his front foot will plant firmly into the ground to form “the immoveable” foundation, from which the entire back-side of his body will be catapulted forward with tremendous force. The extent to which that foot secures the ground while the strength and speed with which the quadriceps muscle of its upper thigh contracts to straighten the entire leg and brace the hip-joint around which the back-side rotates to a frontal position before catapulting forward, determines the initial surge of force from the lower body.NolanRyan 13nolan-ryan 5Tanaka 22Billy_wagner 9Billy W.13
The instant before the front leg is completely straightened, the upper body is arched back and squared to the target while the throwing shoulder and arm are prepared to launch the ball. At that point, the front foot and leg exert their final burst of power, sending the backward arched torso into an explosive forward tumbling action which in turn catapults the outwardly rotated shoulder and corresponding bent arm to deliver the pitched ball with maximum force. If the entire throwing apparatus is precise, and throwing “mechanics” are applied correctly, but the front foot plant is not presented as “immoveable,” but gives way, then the amount of Force to be generated is compromised and cannot attain “maximum” utility.
With regard to Hitting with power, the same principle is involved, the front-foot plant. But the big difference is in the manner in which the second surge of power is administered. During the first stage, the front foot secures the ground (foot pointed 120 degrees to the pitcher-to reduce ankle or knee sprain), with knee slightly bent. The back bent-leg and the front leg work synergistically at this point to induce a rapid turnstile hip-action that concludes with the front leg straightening forcefully as the back bent-knee provides the forward momentum of its backside by the contractual pulling of the groin and “butt” muscles.BarryBonds_bat flatBarry Bonds 42001-10-05-bonds homerun-follow throughC.Davis 6Chris Davis 2
While the front leg is in the process of straightening, the second phase of power has begun with the twisting-torque action of the “Oblique” core-group of muscles as well the entire lower torso. As the shoulders and upper torso are concluding the swing and the bat is ready to contact the ball, the front leg has completely straightened, providing that “immoveable” barrier from which the entire back-side has provided maximum force with which the bat can make contact with the ball.    
 The front foot secures the ground with such force from the straightening front leg that the front hip is being forced open as the back hip is driven forward with equipollence by the aid of a forward driving back bent-knee. If performed properly, the vertical axis of spine and upper body remains constant while the hips are rotating along a consistent horizontal plane. The angle formed, by a diagonal front leg and an upper body and head, as the swing is commencing and concluding is usually 180 degrees or slightly less.
The “turnstile” action of the batter’s swing allows the vertical axis of the body to remain intact, which facilitates the least amount of head movement. The less head movement, the better the batter can detect the nuances of the speeding ball!
Mark McGwire 6Mark McGwire 5
A 450-foot drive, off a well-attuned swing from Mark McGwire, or any good power-hitter, gives reason to applaud a magnificent stroke. But, how is it that they sometimes hit a prodigious “shot” of 500 feet or more? When you really live up to that favorite expression of batters, “I got it all,” your bat made contact with the ball while the body was turning through the swing with the vertical axis intact!  The centripetal force provided by the stable position of the vertical axis produces the powerful centrifugal force, which magnifies the power elicited by the turning hips and shoulders. All of this is predicated on the “front-foot plant” that provides the “immoveable wall” from which all the power is transferred from the “back of the Bus.”
Anecdotal Note:
1.      The Best, and most consistent, means for applying the “front foot plant” is for the batter to refrain from taking a stride. Simply, but forcefully, apply quick and powerful pressure to the front foot and leg to initiate the swing – Least margin for error.
2.      Those batters who incorrectly assume that they need a stride, or high knee kick to initiate their swings will unwittingly compromise the proficiency of their foot plants when good pitchers easily offset their timing with off-speed pitches – greater  margin for  error.

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