How much impact mass does a boxing strike need to compensate for slower speed?

[Username34]

I'm trying to wrap my head around the mass vs speed equation of mechanical power.

If you double mass, you double power. If you double speed, you quadruple power...

Fine, but what does that tell us about the relative importance when things aren't doubled?

Let's say boxing Agent 1: has 3% higher peak speed, than Agent 2. Agent 2 can't improve his speed, but he can add mass... They have the same mass currently and their technique is identical, and will remain identical (so mass can't be tweaked that way)

How much more raw mass does the slower agent 2 need to add in order to topple the mechanical power of Agent 1? And how much does he need to merely equal it?

 

[anuttarasammyak]

There are two measures for motion of body in mechanics.
momentum (vector)
$$m\mathbf{v}$$
and energy
$$\frac{1}{2}mv^2$$
where m is mass and $\mathbf{v}$ is velocity vector. I hope you would brush up your idea along these quantities.

 

[Username34]

There are two measures for motion in mechanics
momentum (vector)
$$m\mathbf{v}$$
and energy
$$\frac{1}{2}mv^2$$
I hope you would brush up your idea along these quantities.

I can't do math. But I do get percentages. Could you answer how much more mass Agent B needs to add, if all else is equal?

 

[anuttarasammyak]

Say
$$\frac{v_1}{v_2}=\frac{103}{100}$$
For equal momentum
$$\frac{m_1}{m_2}=\frac{100}{103}$$
For equal energy
$$\frac{m_1}{m_2}=(\frac{100}{103})^2$$

 

[Username34]

Anybody?

 

[Lnewqban]

@Username34
In order to count, the added mass must move with the speed of impact.
Heavier body does not count, heavier fist does.
Welcome!

 

[Username34]

@Username34
In order to count, the added mass must move with the speed of impact.
Heavier body does not count, heavier fist does.
Welcome!

So, how much heavier does his fist need to be? In percentages?

 

[Username34]

BTW, you must mean arm and fist right? The weight of the arm is surely felt into the target?

 

[Ibix]

So, how much heavier does his fist need to be? In percentages?

As @anuttarasammyak wrote, 3% for equal momentum, 6% for equal energy. You can't have both.

Of course, the heavier arm will accelerate slower, so probably won't reach the same peak speed, so the above calculation is a waste of time. Generally, trying to analyse combat sports with high school physics is a mug's game. The human body is a complex and messy machine and you can't just change one thing without changing other things enough to render this kind of naive analysis invalid.

 

[Borek]

I can't do math. But I do get percentages.

Sorry, it doesn't work this way. You either do it properly, with math and following the physics, or you deceive yourself into thinking you understand.

I am not even sure "power of strike" is something precisely defined, so there is no way to discuss it in a meaningful way.

As it was signaled earlier - you have to analyze the punch in terms of physical properties - energy and momentum. They both depend on speed, but in a different ways.

 

[Username34]

As @anuttarasammyak wrote, 3% for equal momentum, 6% for equal energy. You can't have both.

Of course, the heavier arm will accelerate slower, so probably won't reach the same peak speed, so the above calculation is a waste of time.

Why is it of course that a heavier arm accelerates slower? A heavier arm has more muscle to generate momentum.

And it doesn't matter anyway since the task is to calculate how much mass you need to add even if it actually slows down the punch even more.

 

[Username34]

As it was signaled earlier - you have to analyze the punch in terms of physical properties - energy and momentum. They both depend on speed, but in a different ways.

Is a kick generally always more powerful than a fast punch due to penetrating deeper, with stronger support muscles? Os is 15% mass of the body vs 5% more than enough to compensate speed disadvantage regardless of how you penetrate?

 

[Username34]

The human body is a complex and messy machine and you can't just change one thing without changing other things enough to render this kind of naive analysis invalid.

I thought you could do anything in a hypotethical.

 

[Ibix]

Why is it of course that a heavier arm accelerates slower? A heavier arm has more muscle to generate momentum.

Depends why it's heavier. You can just add fat. And your assumption that it's muscle highlights the issue: can you assume that adding 3% of the current mass of muscle and bone increases the available force by 3%? If it doesn't you don't get the same speed. It may be more, it may be less. You need that kind of detail to answer your question.

I thought you could do anything in a hypotethical.

Sure. But unless your hypothetical situation has some connection to reality, what's the point?

 

[Username34]

Depends why it's heavier. You can just add fat. And your assumption that it's muscle highlights the issue: can you assume that adding 3% of the current mass of muscle and bone increases the available force by 3%? If it doesn't you don't get the same speed.

But you don't need to sustain your current speed or replicate Agent A's speed to equal or top his power. You can go the mass pathway instead.

Just make a rough estimate how much you believe speed is lost.

 

[Borek]

more powerful

You never defined what "power" means in this context, so the discussion is just hand waving.

Yes, there is some intuition behind - we expect kick to do more damage than punch - but as long as you don't define what it is that you are measuring (what is the "damage"?), you are just wasting time looking for any numbers. And saying "percentages will be enough" doesn't make any sense - you can calculate percentage of some well defined amount, but not of some hand wavy intuition.

 

[Username34]

You never defined what "power" means in this context, so the discussion is just hand waving.

Yes, there is some intuition behind - we expect kick to do more damage than punch - but as long as you don't define what it is that you are measuring (what is the "damage"?), you are just wasting time looking for any numbers. And saying "percentages will be enough" doesn't make any sense - you can calculate percentage of some well defined amount, but not of some hand wavy intuition.

"In physics, power is the amount of energy transferred or converted per unit time."

 

[Borek]

"In physics, power is the amount of energy transferred or converted per unit time."

That's what physics understands as power, yes, but it is not related to the damage done. You can get GW power from very short laser pulses - pulses, that use pretty small amounts of energy, and won't even make a blister (assuming they hit skin). At the same time industrial laser with power in a few kW range will easily cut off any limb on a minute time scale.

But even assuming power is just that. How do you define time involved? How do you measure or calculate it?

How do you measure or calculate amount of energy transferred?

 

[Lnewqban]

BTW, you must mean arm and fist right? The weight of the arm is surely felt into the target?

Not necessarily.
No significative impact is induced by hitting the target with the forearm instead.
The center of mass of the arm is always moving at a slower speed than the fist (unless for a hook or a swing).

It requires practice and good technique to make the momentum of the slower parts of the body (legs, torso, shoulders, arms) to reach the knuckles at the instant of impact.

Note how the right-side fighter lifts his right knee to increase the total momentum that will reach the fist at the exact time.



Nunchakus and sticks are effective because the tips can strike very fast and reach neuralgic points.
A very quick transfer of mechanical energy is what interrupts nerves transmission and damages tissue.

Please, see:
https://boxingscience.co.uk/science-behind-punch/

 

[Vanadium 50]

"Senatorr Blowhard has a lot of momentum in his latest campaign."

That does not mean that he has a lot of mass times velocity. Power is the same way. You are not going to map everyday terms onto physics equations and get anything sensible out, I am afraid.

 

[Username34]

That's what physics understands as power, yes, but it is not related to the damage done. You can get GW power from very short laser pulses - pulses, that use pretty small amounts of energy, and won't even make a blister (assuming they hit skin). At the same time industrial laser with power in few kW range will easily cut off any limb on a minute time scale.

But even assuming power is just that. How do you define time involved? How do you measure or calculate it?

How do you measure or calculate amount of energy transferred?

You calculate the time it took from initiation to impact. And you calculate the weight of the tool used.

Like I said, for the purposes of this question, technical delivery of the punch is exactly the same. The only variable is speed and weight of the agent.

 

[Username34]

Just as a side note: in martial arts, you can use something called angular momentum to increase the weight of the strike into the target.

Thus a lighter person can actually deliver more weight than the heavier if he used angular momentum to greater effect than the heavier person.

And a lighter person can also generate greater mechanical power this way if he does it faster than the heavier guy.

Light guys with long legs/arms can get the best of both worlds - leverage/weight and speed.

 

[Username34]

Here's the hardest hitting punching boxer EVER using it using his skinny arms to his advantage. this

 

[Borek]

You calculate the time it took from initiation to impact.

I am not sure what you mean. What is the initiation? The moment you start to move hand/leg/whatever? If so, time between initiation and impact can be used to calculate the power used to accelerate the hitting part (hand, foot, knee, whatever), and is not easily related to the energy/momentum delivered to the target - and that was my understanding of the punch power. As I told you, we can have intuitions, but as long we don't define precisely what we are talking about we are just waving hands.

Besides, you have silently ignored what I told you about why comparing powers is a nonsensical exercise. Being selective about what you agree with is not a way forward.

Just as a side note: in martial arts, you can use something called angular momentum

Angular momentum is a perfectly well defined physical concept, not "something used in martial arts".

You will really, really do much better if you start with learning Physics101. Right now this discussion is a waste of time.

 

[Username34]

I am not sure what you mean. What is the initiation? The moment you start to move hand/leg/whatever? If so, time between initiation and impact can be used to calculate the power used to accelerate the hitting part (hand, foot, knee, whatever), and is not easily related to the energy/momentum delivered to the target - and that was my understanding of the punch power. As I told you, we can have intuitions, but as long we don't define precisely what we are talking about we are just waving hands.

Besides, you have silently ignored what I told you about why comparing powers is a nonsensical exercise. Being selective about what you agree with is not a way forward.
Angular momentum is a perfectly well defined physical concept, not "something used in martial arts".

You will really, really do much better if you start with learning Physics101. Right now this discussion is a waste of time.

Explain to me why putting on weight will make the object move slower?

Mike Tyson has heavy bones and he could still moves his hands at this speed. There is no physical law that dictates that heavier hands move slower.. and I doubt he could move faster than that..

 

[BWV]

Nunchakus and sticks are effective because the tips can strike very fast and reach neuralgic points.
A very quick transfer of mechanical energy is what interrupts nerves transmission and damages tissue.

Please, see:
https://boxingscience.co.uk/science-behind-punch/

Actually nunchucks are worthless weapons because.. physics.. -> all speed and no mass

Stick > nunchucks:

 

[Ibix]

Mike Tyson has heavy bones and he could still moves his hands at this speed.

And if I had Mike Tyson's muscles and my twiggy bones I'd move faster than him, because I'd be lighter and would accelerate faster under the same force. Assuming I could apply that much force to a weaker skeleton without damaging things. And assuming I could develop Tyson's muscles without increasing bone density from the heavy bag.

This is the problem here: you can't really change one thing (just give me Tyson's muscles) without changing others in ways we have no data to predict. So a naive model is pretty much pointless. Even if you could work out what the figure (or figures) of merit are for a punch.