The Science Behind a Punch
By Reylan Loberternos
Sat, 19 Sep 2009
This article shows proof that Manny “Pacman” Pacquiao is also a genius in physics. How some important factors in the sport of boxing such as speed, fist-mass, technique, and even the gloves used affect the effectiveness of a punch are also comprehensively discussed in this piece.
Tungod, Inabanga, Bohol – A punch is often associated by boxing experts and aficionados with the concept of force and power. We regularly hear these terms mentioned by boxing commentators in their blow by blow account of a boxing match, though technically, their definitions of force and power aren’t exactly what they mean in physics, strictly speaking. Nevertheless, it is most certainly refreshing to incorporate a little bit of physics into some aspects of boxing. After all, boxing is also science in itself – the sweet science.
But worry not because in this article, I won’t subject you to mind-boggling calculations; much less force you into a state of induced headache.
Anyway, I believe that there is an easier way to make comparisons between punches than through the concept of force… and that is through the concept of momentum. Simply put, momentum p is the product of a moving object’s mass m and its velocity v. In this particular case, the object referred to is the fist.
p = mv (momentum = mass x velocity)
The bigger the momentum, the bigger the force of impact and consequently, the bigger the damage inflicted as well. This is probably the reason why big punchers like Roberto “Hands of Stone” Duran are called heavy-handed, while boxers like Malignaggi are called feather-fisted. In addition, this is also the reason why boxers in the heavier weight class tend to hurt those in the lower weight class more effectively than the other way around. Therefore, this makes the creation of weight divisions necessary. Mass and velocity (or speed) are two parameters that affect momentum. For people of the same weight, speed is the determining factor. However, please take note that these general statements only consider a stationary target, to save ourselves from the more complicated concept of impulse (change in momentum), and make things a whole lot simpler. Nonetheless, for those who are interested, this concept is discussed a little bit later in the article.
We can also use the concept of momentum in differentiating the impact of a jab and a power-punch. A jab only utilizes the weight (or mass, to be technically correct) of the fist and the arm, while a power punch utilizes the weight of the whole body, which translates to a bigger momentum upon impact and more damage inflicted.
If you take a closer look, the explanation above isn’t really meant to make any exact calculations. Rather, its primary purpose is to show a scientific proof that mass(or weight) and speed are determining factors on how much damage a punch can inflict. Of course you can argue technique and all other factors you can think of. Using the right technique, a boxer can use as much body weight as he can in throwing his punch or he could just sit on his punches or throw arm punches that are much quicker but with less weight, thus, less damage, but the bottom line is still speed and weight (mass).
Now let’s consider adding more variables like defense, gloves used, and technique in throwing the punch. The latter two are factors that the one throwing the punch can control while defense is one thing that the person taking the punch can do to minimize the damage. Here the concept of the change in momentum comes into play.
Remember that we are no longer considering a stationary target and the cushion on the gloves also becomes an additional variable to consider. This therefore becomes a topic about collision, which suggests that it is no longer enough to consider force, or momentum, but the whole impulse-momentum equation given by the equation below
integral of Fdt = integral of dp
where F is the force, dt is the time derivative and dp is the derivative of momentum.
If we assume that the force is constant throughout the collision event (from the moment the glove first touches the target to the moment the glove first leaves the target), the above equation simplifies to
Δp = F Δt or F = Δp/Δt
To give a more vivid example, let me borrow an example given by my good friend nbajr2003 or Pacland. Consider two identical eggs dropped from the same height. One falls on concrete floor while the other falls on a pond. in which case does the egg break?
In both cases, the egg’s change in momentum is the same. They are dropped from the same height, so they both have the same zero initial speeds, and the same speeds just before impact with the ground or the lake. However, the force is applied much more gradually in the second case than in the first case. As a result, the egg breaks in the first case and not in the second case. In boxing, the cushion in the gloves serves to prolong the application of that force, to lessen the damage on the puncher’s knuckles. This is probably the reason why pound for pound king Manny “Pacman” Pacquiao prefers to use the Cleto Reyes gloves because of its less padding, which, based on the above explanations, translates to more damage inflicted by his punches than when he uses a glove with more padding like the Everlast or Winning gloves. Pacquiao, though probably lacking in formal education, certainly knows his physics!
Now let’s consider the defensive capability of the one receiving the punch. Good defensive boxers lessen the impact of their opponent’s punches by moving their heads backward against a straight punch or turning their head sideways in the same direction as a hook they will receive. Usually when they don’t see the punch, they get caught while moving their heads opposite the direction of the punch. Here, the punch is more devastating and usually result to a knockout.
Now going back to F = Δp/Δt, if a boxer can create a potent combination of a greater change in momentum at a lesser amount of time, then that would correspond to greater force, and greater damage!
I hope I didn’t confuse you more.
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Editor's Note: Reylan Loberternos is currently taking up graduate studies for Master of Science in Physics at the University of San Carlos in Cebu, Philippines. Reylan is also a long-time member of the Pacland / PhilBoxing Forum and is one of its moderators.
Click here to view a list of other articles written by Reylan Loberternos.
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