Hand size punching power

[jeremyemilio]

According to a less than reliable source I just Googled, the average mass of a human hand is somewhere between about 300-600g. That, to me, sounds like a 100-200g difference would be huge in generating momentum. Yes, you use a lot of angular momentum as well, but even then L = r x mv, so mass still has a great effect on momentum. Generating torque with your body is about increasing the velocity of your punch, so while your legs/core help with moving your hand as fast as possible, it is still your hand that is landing on your opponent and causing the change in momentum. I think the difference is much greater than 0.5%, to be honest.

You are correct.

 

[Matt4786]

This would be quite a feat.

And if you are suggesting that increasing the weight of the object delivering the impact (i.e. the HAND itself) by 30 - 70 per cent is going to have a negligible effect on the force of that impact (whether that impact is the product of rotational/angular momentum, as with a hook, or linear momentum, as with a straight right) you need to redo your calculations.

But if you are simply doing your calculations as if it is the entire body of the fighter that is building momentum and making impact, then you just need to go back for more education.

See...you are treating a punch like a mass, connected by a massless string to an axis of rotation. The entire body of the fighter contributes to the moment of inertia. And angular momentum = moment of inertia * angular velocity. Even If it did work like a mass on a string, the increase in mass would be much less than 30-70%. More like 10%, unless the guy has anvils for hands. I'm gonna keep this civil, as I don't believe in ad hominem arguments or false appeals to aurthority. Simply put, you are approaching this problem the wrong way. I suggest you do the integrals for moment of inertia. Now for the issue of linear momentum, it's the same. We have to consider the entire mass, not just the point of mass making impact.

 

[jeremyemilio]

You made alot of good points that I was going to make in relation to velocity and acceleration and also the ability to move a heavier hand.

But imo big or small hands is inconsequential, given a proper punch involves torquing and using the momentum in your entire body, a 100g-200g difference in hand mass is inconsequential, it would probably be a 0.5% difference in the grand scheme of things.

Hitting a ball with a bat properly also involves torquing your entire body... but the momentum (in the case of hitting a ball and throwing a punch) is built almost entirely in the bat/fist.

Hit a fastball with a broomstick if you want to see just how little of your hitting momentum is actually being built up up in your body. Or hit a nail with a spoon.

To generate driving force you need to build momentum in the object or part of the object that is making the impact.

 

[Matt4786]

Hitting a ball with a bat properly also involves torquing your entire body... but the momentum (in the case of hitting a ball and throwing a punch) is built almost entirely in the bat/fist.

Hit a fastball with a broomstick if you want to see just how little of your hitting momentum is actually being built up up in your body. Or hit a nail with a spoon.

To generate driving force you need to build momentum in the object or part of the object that is making the impact.

But that's a much different integral because the radius associated with the mass of the bat is much further from the axis of rotation than the radius between the axis and the hand so it's m*r value is gonna be much larger and be a much larger portion of the integral. A bat is also much heavier than a hand, further increasing the product of m*r

 

[jeremyemilio]

See...you are treating a punch like a mass, connected by a massless string to an axis of rotation. The entire body of the fighter contributes to the moment of inertia. And angular momentum = moment of inertia * angular velocity. Even If it did work like a mass on a string, the increase in mass would be much less than 30-70%. More like 10%, unless the guy has anvils for hands. I'm gonna keep this civil, as I don't believe in ad hominem arguments or false appeals to aurthority. Simply put, you are approaching this problem the wrong way. I suggest you do the integrals for moment of inertia. Now for the issue of linear momentum, it's the same. We have to consider the entire mass, not just the point of mass making impact.

As I suggested above, I'm going to suggest you try your hand at driving a nail with a spoon. And then come back and tell me that I should be doing my calculations with "the entire body of the fighter."

The entire body of the fighter serves as a fulcrum and an anchor and even as a source of power. But the entire body of the fighter isn't building up very much momentum. All of which means that if the striking object (in this case the fist) has not built up very much momentum, the inertia of the object being struck is going to make itself known.

And a guy with large hands easily has 30%-70% more total mass in his hands than a guy with small hands. Where do you come from that there's only a 10% differential in hand size? There are individual people with a 10% difference in the size of their own two hands.

 

[Matt4786]

As I suggested above, I'm going to suggest you try your hand at driving a nail with a spoon. And then come back and tell me that I should be doing my calculations with "the entire body of the fighter."

See my response to that.

The entire body of the fighter serves as a fulcrum and an anchor and even as a source of power. But the entire body of the fighter isn't building up very much momentum. All of which means that if the striking object (in this case the fist) has not built up very much momentum, the inertia of the object being struck is going to make itself known.

Why don't you do the integral? That's not correct. the mdr values will add up. Do the integral.

And a guy with large hands easily has 30%-70% more total mass in his hands than a guy with small hands. Where do you come from that there's only a 10% differential in hand size? There are individual people with a 10% difference in the size of their own two hands.

70% is way too high for this example, but I would concede 30%. Either way, it doesn't matter. A fist on a string connected to a rod (i.e. an axis of rotation contributing no mass to the moment of inertia) with the same angular velocity and radius as a guy punching isn't gonna knock someone on their ass. Just think about it....no calculation necessary. Why? The person has a much larger moment of inertia and the majority of this is not derived from a hand, which is less than 1% of a person's mass.

 

[jeremyemilio]

But that's a much different integral because the radius associated with the mass of the bat is much further from the axis of rotation than the radius between the axis and the hand so it's m*r value is gonna be much larger and be a much larger portion of the integral. A bat is also much heavier than a hand, further increasing the product of m*r

Yes, yes. But the same rules apply. The bat analogy is used to make the rule apparent in a more pronounced way. The hammer/spoon analogy brings the radius much closer (1.5-2 feet), but to the same effect. Come in another 8 inches to a foot and we're at the end of the arm. The distance between axis and radius got somewhat shorter, but it's still significant. I didn't disappear.

In fact, forget the bat and the hammer. Hold a rock in your hand. Swung with everything you have, which is going to deliver a greater impact, a 1 lb rock or a 2 lb rock?

Aside from all of that, what you are missing is that the fist is the only thing that is really going through any significant range of motion and, thus, the primary tool for building the momentum to be used in the impact. In fact, we've all seen guys knock people out while moving their bodies backwards.

A larger/heavier fist means greater momentum which makes for a greater impact.

 

[obroin]

Matt,

I see your point about a punch involving more mass than just the hand. But, in the calculations of moment of inertia, the hand is furthest from the rotational center. So when we consider I = mr^2, the mass furthest away (the hand) is going to contribute the most to the moment of inertia. I know this is for a point particle, but I think the principal is still sound.

Also, we're not arguing that there is more going on than just hand size in generating punching power. For example, if I lunge forward right as I'm throwing, my fist will be traveling at Vfist + Vbody, so it's going to have a lot more momentum. But if you take one guy and have him throw the same exact punch but with larger or smaller hands, he'll hit harder with bigger hands. Carwin hit like a fucking atom bomb because his fists were enormous and he knew how to throw a proper punch with power. That is the reason Carwin seemed to knock people senseless with small, short punches.

 

[Matt4786]

Yes, yes. But the same rules apply. The bat analogy is used to make the rule apparent in a more pronounced way. The hammer/spoon analogy brings the radius much closer (1.5-2 feet), but to the same effect. Come in another 8 inches to a foot and we're at the end of the arm. The distance between axis and radius got somewhat shorter, but it's still significant. I didn't disappear.

In fact, forget the bat and the hammer. Hold a rock in your hand. Swung with everything you have, which is going to deliver a greater impact, a 1 lb rock or a 2 lb rock?

Aside from all of that, what you are missing is that the fist is the only thing that is really going through any significant range of motion and, thus, the primary tool for building the momentum to be used in the impact. In fact, we've all seen guys knock people out while moving their bodies backwards.

A larger/heavier fist means greater momentum which makes for a greater impact.

Ok the rock example...it also is not germaine, since we are doubling, even tripling the weight at the end of the rotation, rather than a 30% increase. It's true that angular momentum increases with radius, but hands just aren't heavy enough to shift the moment of inertia considerably. I'm almost of a mind to just brush off my Calc II and do a simplified calculation with a rod.

See I think you are neglecting the rest of the body, which is also being significantly rotated, and also contains a lot of mass.

In the example of purely fists, the difference mdr is negligible and the math shows it....I don't know what else to say about that.

At the end of the day, neither pressure or hand mass contribute much. It's power that matters, i.e. how much force can be delivered in a moment. Someone like Brock Lesnar, despite big hands, could never punch to his full potential because he pushed his punches rather than "exploding" them on the target, which meant a much larger denominator for F/t.

 

[Matt4786]

Matt,

I see your point about a punch involving more mass than just the hand. But, in the calculations of moment of inertia, the hand is furthest from the rotational center. So when we consider I = mr^2, the mass furthest away (the hand) is going to contribute the most to the moment of inertia. I know this is for a point particle, but I think the principal is still sound.

Also, we're not arguing that there is more going on than just hand size in generating punching power. For example, if I lunge forward right as I'm throwing, my fist will be traveling at Vfist + Vbody, so it's going to have a lot more momentum. But if you take one guy and have him throw the same exact punch but with larger or smaller hands, he'll hit harder with bigger hands. Carwin hit like a fucking atom bomb because his fists were enormous and he knew how to throw a proper punch with power. That is the reason Carwin seemed to knock people senseless with small, short punches.

Can you just do me a favor because I'm too lazy. Do the integral for a rod of relatively uniform mass, weighing about 180 lbs (80kg). Do it both with and without 100 grams added to the end, with a maximum radius of a meter. I somehow doubt the difference in moment of Inertia will be significant. If it is, I will concede my point.

 

[jeremyemilio]

See my response to that.



Why don't you do the integral? That's not correct. the mdr values will add up. Do the integral.



70% is way too high for this example, but I would concede 30%. Either way, it doesn't matter. A fist on a string connected to a rod (i.e. an axis of rotation contributing no mass to the moment of inertia) with the same angular velocity and radius as a guy punching isn't gonna knock someone on their ass. Just think about it....no calculation necessary. Why? The person has a much larger moment of inertia and the majority of this is not derived from a hand, which is less than 1% of a person's mass.

Time to just admit we've come to an impasse. The sticking point isn't the physics; it's that what I believe to be happening when a fighter throws a punch (or when most fighters throw most punches) differs from what you believe to be happening.

I think you are overestimating torque. A perfectly thrown hook in a gym against a heavy bag by a world class boxer? Sure. I'll do the integral... and we'll probably come up with similar numbers (although even there there's a lot of guess work... it's not like you can just assume the amount of force a guy is delivering based on his weight... things like muscle strength and even bone density come into play).

But the majority of punches have differing, and often significant, amounts of ball and string action going on.

If I might jump ship on the physics argument for just a moment, I've played sports all my life and in my experience, there's no such thing as 'light sparing' with a guy who has really big hands. Even a successfully blocking a shot your shoulder can knock you off balance. Same phenomenon when a ham fisted guy on your football team taps you on the helmet after you make a good play.

Anecdotal, I know. Maybe it's just those particular guys and has nothing to do with the size of their hand. But I feel I've earned the right to a bit of that.

 

[bunchof66]

bunch of science dorks in here with interesting stuff to say about physics (for real, good stuff guys) but it's all pretty irrelevant i think

technique plays a bigger part than any but the most drastic physical differences will.

for instance, footwork >>>>> fist size.

i think the closest factor first size is gonna is that (iirc) big hands could be indicative of a thicker bone structure, which would mean the fighter has much less risk of breaking their hands and can not only punch with reckless abandon during the fight but also during training.

for more about that read the article about pacquiao's wrist size. he's got 8 inch circumference wrists. for some perspective i am 6'6" and mine are 7.5"!

 

[obroin]

Can you just do me a favor because I'm too lazy. Do the integral for a rod of relatively uniform mass, weighing about 180 lbs (80kg). Do it both with and without 100 grams added to the end. I somehow doubt the difference in moment of Inertia will be significant. If it is, I will concede my point.

Damn my calculus is a little rusty. How long are we assuming the rod is? Given your asking for 80 kg, I'm assuming you mean a whole body. So lets just say six feet (1.83m) for these calculations.

80 kg / 1.83 m = mass density (p) of 44 kg/m.

The formula for the integral then is

I = {p*r^2 dR from 0-1.83m

Given mass density p is constant, the indefinite integral of p*r^2 dr is p/3 * r^3. Thus

(p/3) (1.83^3 - 0^3) = (44 * 6.13) / 3 = 90 kg * m^2

Now, given that were assuming the 100g is a "point" at the end of the rod, we can calculate it separately.

I = m*r^2
I = .1kg * 1.83^2 = 0.33 kg * m^2. (3.67% of whole mass)

which is much less than 90, BUT this does not accurately describe the situation we're looking at. That would basically be the difference between grabbing the guy at his feet and spinning him in a circle and doing the same thing with a heavier fist.

 

[bunchof66]

also tho I'll bet i can punch harder than any of the punches Anderson Silva has scored KOs in the ufc with.

you don't have to blast someone's head off, you h just have to time it and catch em when they don't expect it. the physics of hand size is superfluous in any discussion about realistic factors that make a difference in a fighters ability to knock others out

 

[Matt4786]

edit. Obroin's calc was better, but still proves the general point, even if it's a vastly simplified approach.

 

[jeremyemilio]

Can you just do me a favor because I'm too lazy. Do the integral for a rod of relatively uniform mass, weighing about 180 lbs (80kg). Do it both with and without 100 grams added to the end, with a maximum radius of a meter. I somehow doubt the difference in moment of Inertia will be significant. If it is, I will concede my point.

This is such an odd calculation for representing what is happening when someone throws a punch. Go back to the rock example I gave earlier. Would your really calculate relative impact of hitting something with a 1 lb rock vs hitting something with a 2 lb rock by doing an integral for a rod of relatively uniform mass weighing 180 lbs vs doing an integral based on 181 lbs?

 

[jeremyemilio]

Damn my calculus is a little rusty. How long are we assuming the rod is? Given your asking for 80 kg, I'm assuming you mean a whole body. So lets just say six feet (1.83m) for these calculations.

80 kg / 1.83 m = mass density (p) of 44 kg/m.

The formula for the integral then is

I = {p*r^2 dR from 0-1.83m

Given mass density p is constant, the indefinite integral of p*r^2 dr is p/3 * r^3. Thus

(p/3) (1.83^3 - 0^3) = (44 * 6.13) / 3 = 90 kg * m^2

Now, given that were assuming the 100g is a "point" at the end of the rod, we can calculate it separately.

I = m*r^2
I = .1kg * 1.83^2 = 0.33 kg * m^2. (3.67% of whole mass)

which is much less than 90, BUT this does not accurately describe the situation we're looking at. That would basically be the difference between grabbing the guy at his feet and spinning him in a circle and doing the same thing with a heavier fist.

Yup.

Wow.

And I thought Matt was just overestimating the significance of torque v momentum.

No wonder we can't get on the same page.

 

[Matt4786]

This is such an odd calculation for representing what is happening when someone throws a punch. Go back to the rock example I gave earlier. Would your really calculate relative impact of hitting something with a 1 lb rock vs hitting something with a 2 lb rock by doing an integral for a rod of relatively uniform mass weighing 180 lbs vs doing an integral based on 181 lbs?

Well you also have to factor in stuff like hardness with a rock, which affects power. A rock has a lot less give than a fist which should equate to a shorter time of impact. This is obviously too complicated to just pin down w/ something like F=ma, but that being said, an integral for moment of inertia would inevitably be part of the calculation, and that calculation shows that if all things are considered equal (the premise we started with), the difference in angular momentum is minimal. I only used that calculation since you were making a rotational argument. That being said, it doesn't support your claim.

 

[djacobox372]

Core size = punching power --this is why Dan Henderson hits so hard, his core is freakishly strong.

Whenever I'm watching a fighter I don't know I just look at how thick/solid his core is to give me a clue as to how hard he can hit. How "ripped" he is doesn't matter.

Lanky guys with a strong core are absolute monster punchers, due to the added advantage of leverage = the speed at the end of a longer lever is much faster than that of a shorter one.

 

[Charlitos1988]

He would have to accelerate like 3 times faster than Brock, which just isn't happening.

Also, debating the veracity of F=MA is a bold strategy.

so there's a limit of the acceleration you can reach as a human being? mmm