Is it possible to knock someone out with a jab

[Flying Crane]

If we ignore crumple zones and imagine they are exactly head-on (opposite trajectories), the car traveling at 50 mph is slowed 20% faster than if it hit a stationary object, so takes more force. Likewise, the reflective movement of that car likely increases the deceleration time for the 60 mph car, so it takes a bit less force.

I expect to be enrolling in some undergrad physics courses in a year or two, hope to get a better grasp of these issues then.

 

[Tony Dismukes]

The thing you're all forgetting is time. If you hit me, and I move away, your fist (and my body) are still subject to exactly the same amount of energy. What's different is the time. Moving away means it takes longer for the same amount of kinetic energy to transferred from your fist to my body. That is what renders your punch less effective.

Not forgetting about time at all. We're discussing impact. Impact is measured in units of force. Force is inversely proportional to the time required to accelerate/decelerate a mass. As you say, moving away means that the acceleration from the blow takes longer, which means the force of impact is less.

When two objects moving in opposite directions collide, they both come to a stop immediately. Just as if they'd hit a wall. And with the same damage as if they'd hit a wall.

Yep, hitting an oncoming object of equal mass and opposite velocity is like hitting a wall. As I noted above, hitting a stationary object which is not locked in place is different. Even if the collision brings the moving object to a complete stop (which won't necessarily happen, depending on the masses involved), the struck object will move somewhat, which means the time of deceleration for the moving object will take longer, which means the force is less, which means the impact is less.

The energy of the two objects is not cumulative.

Actually, it is, as I noted above. If the masses and speeds are the same, then the kinetic energy involved in the collision of the 2 objects will be twice that of one object colliding with a wall. However that kinetic energy is equally split between deforming object A and object B, so each object takes the same damage as if it had collided with a wall. 2 x 1/2 = 1.

(Another way to put it is that even though the wall applies a force equal to that of an object moving in the opposite direction, the wall itself is not moving so it has no kinetic energy.)

This is fun. To think through this I had to dig out physics knowledge I haven't used since college. Makes me want to pull out my old textbooks.

 

[Phobius]

Don't grovel. It's demeaning.
And begging won't change how physics works.

True, so dont be wrong.

That is the statement I responded to. That statement is wrong. If you'd like to discuss physiology instead of physics, that's fine. Since that is what my degrees are in, I'm more at home there than pure physics anyway.

The statement you responded to was however if not completely true your response was incorrect.

It's really not complicated at all. An object moving at speed X has Y amount of kinetic energy. Decelerating that object from X to zero requires exactly that much energy. It doesn't matter if the object you're hitting is moving towards you, away from you, or stationary.

You are missing the key thing of any physics class/course or whatever you call it. The total sum of all force vectors are zero. You can not rule out the object that is being hit by the impact. Reason you can do so with a wall is because it is connected to ground and has a material toughness strong enough to withstand those forces and pass them into the earth or whatever it goes depending on the construction. Force does not disappear but are instead resulting in a larger deformation of the crashing object.

Problem is if object being hit can not withstand those forces without folding, deforming or otherwise moving in some way. Equation differs greatly and deformation or impact effect is spread out between the two objects. Either resulting in larger deformation or acceleration.

So two objects moving at a speed of X will result in a total force of impact larger than if one object moves at a speed of X and other at speed of 0. At impact the larger force that needs to be spread or nullified will result in greater damage.

Actually if the wall could move at a speed of X into a car at speed of X the impact would be a lot higher on the car, reason being that the wall can be deemed as reflecting the complete force back into the car. Sort of like an infinite field. So if wall moved at speed of X into a car moving at speed of X. This effect would be same as car running into a stationary wall at 2X speed.

This really is beginner physics.

 

[JR 137]

Even if the collision brings the moving object to a complete stop (which won't necessarily happen, depending on the masses involved), the struck object will move somewhat, which means the time of deceleration for the moving object will take longer, which means the force is less, which means the impact is less.

This is fun. To think through this I had to dig out physics knowledge I haven't used since college. Makes me want to pull out my old textbooks.

Just a point of order...

If the two cars hit each other head on and bounced backward, technically, they did stop. For a fraction of a second, they had to stop in order to change direction. It can't be seen with the eye, but it does happen. A baseball briefly stops (and flattens out) when it hits a bat before to goes off into the stands; throw a ball straight into the air, and it stops before coming back down.

The car has to stop traveling in one direction before changing direction, otherwise it wouldn't change direction. Now, if it changes direction at an angle, i.e. traveling due north, got hit, and went NNE, then it didn't completely stop in the north direction because there's still a north component to its direction. But if it was traveling due north and the impact changed its direction to south (at any angle of south), then it completely stopped beforehand.

Yep, college physics was fun. Teaching physics in my middle school science classes is my favorite unit. My degree is biology with sports medicine, so this type of physics isn't my strongest suit.

 

[marques]

Of course it is possible. And some guys are experts on that.
Just human head can absorb quite heavy strikes on the front. Anything (jab, cross, hook, kick...) to the side of the head is a easier KO. (The hard here is getting the side.)

 

[Gnarlie]

Can we change the logo on threads like this to read "Martial Geeks"?

Martial Dork

Sent from my Nexus 6P using Tapatalk

 

[Tiger84]

You always hear people saying a jab is not a knockout punch but I think if you time it right it can be. No it's never going to be as powerful as a cross or a hook you can still get a lot of power into especially if you step into it. Also it's a harder punch to see coming and the ones that hurt most are the ones you don't see.

I think the best option to get a ko with it is if they're moving forward and you use the opposing force of them coming in to hit them. For example if a car hits another car that's parked at 40 miles an hour that's 40 miles am hour worth of damage but if both cars are going 40 mph when they hit each other that's 80 mph worth of damage. Same goes for your punching.

An example of this is Forrest griffin vs Anderson silva

It is certainly possible but generally unintentional.

 

[Kickboxer101]

Martial Dork

Sent from my Nexus 6P using Tapatalk

Yeah I stopped bothering to read my own thread I'm to dumb to understand most of this lol

 

[Dirty Dog]

Venn diagrams always help these technical discussions...

 

[JP3]

You guys do realize you've totally hijacked this thread, right?

 

[Dirty Dog]

Since the OP asked "can you knock someone out with a jab" and then proceeded to answer their own question with a video of someone doing exactly that, it was sort of a pointless thread to begin with, and destined to be hijacked.

 

[RTKDCMB]

if a car hits another car that's parked at 40 miles an hour

Not sure how a car can be parked at 40 miles per hour.

Actually, that's not how physics works.

Actually it is.

The impact from hitting a stationary object vs a moving object is the same.

As long as the resultant velocity is the same.

I am not a physics person

Fortunately I am.

It's really not complicated at all. An object moving at speed X has Y amount of kinetic energy. Decelerating that object from X to zero requires exactly that much energy. It doesn't matter if the object you're hitting is moving towards you, away from you, or stationary.

You are a little muddled up as to where this statement (which is correct) applies. Two identical cars traveling at 40 mph towards each other will have the same impact force as one car traveling towards a stationary car at 80 mph not 40 mph. Both cars will accelerate away from each other in opposite directions at the same velocity if they were both moving at the same velocity toward each other. With the stationary car it would accelerate away from the moving car whilst it would become stationary. Assuming a completely ealstic collision in both cases.

crumple zones

The purpose of crumple zones is to spread out the contact point of the impact over a longer period of time thus reducing the power (change in kinetic energy over time) experienced by the driver..

 

[Gerry Seymour]

Not sure how a car can be parked at 40 miles per hour.

I saw that as I typed it, and it made me laugh, so I left it unclarified.

The purpose of crumple zones is to spread out the contact point of the impact over a longer period of time thus reducing the power (change in kinetic energy over time) experienced by the driver..

This. So it's not a change in total force, but in force delivered to the occupants. Boxing gloves and headgear do the same thing.

 

[Buka]

I have seen people knocked out with everything over the years.

Not sure if any of them had an understanding of physics.

 

[Kickboxer101]

Since the OP asked "can you knock someone out with a jab" and then proceeded to answer their own question with a video of someone doing exactly that, it was sort of a pointless thread to begin with, and destined to be hijacked.

Not really since it wasnt actually a ko the guy was still conscious he just quit he waved it off as he went down

 

[oftheherd1]

No, I did not mis-state at all.

Yes, it is counter-intuitive. It is, nonetheless, how physics works.

When object A is traveling at speed X and strikes object B, it decelerates from X to zero. The deceleration forces are identical regardless of if object B is stationary or moving.

If you'd like to argue with Newton, feel free. But in this universe, that is how the physics works.

OK, now I see it. Each car is an immovable object for the other (mass and speed being as nearly equal as possible). Amazing what one can learn. Thanks for the links.

 

[SenseiHitman]

I know for a fact the jab can knock someone out from my own experience. When I was an amateur kick boxer, I fought in the UAKF here in PHX back in the late 1990s and early 2000 and I won my first fight in the first round by the 3 knock down rule and one of the knock downs was from my jab. In my second fight, I knocked an opponent out cold with a jab and he stayed down for a long time and he was out before he hit the floor. I even was able to daze and knock into the ropes the champion of my division with my jab. That fight was declared a draw and it was the only one I went the distance. I won the rest by way of knockout. I think the fact I am left handed helped with the accuracy and that when I hit someone with a kick punch or whatever, I do it as if it may be my last chance.

 

[Kickboxer101]

I know for a fact the jab can knock someone out from my own experience. When I was an amateur kick boxer, I fought in the UAKF here in PHX back in the late 1990s and early 2000 and I won my first fight in the first round by the 3 knock down rule and one of the knock downs was from my jab. In my second fight, I knocked an opponent out cold with a jab and he stayed down for a long time and he was out before he hit the floor. I even was able to daze and knock into the ropes the champion of my division with my jab. That fight was declared a draw and it was the only one I went the distance. I won the rest by way of knockout. I think the fact I am left handed helped with the accuracy and that when I hit someone with a kick punch or whatever, I do it as if it may be my last chance.

Nice how long did you fight for competitively?

 

[SenseiHitman]

I fought 4 times amateur kickboxing,1 time shoot fighting, 5 times rage in the cage all here in Tucson or Phx from 1997 to 2000.

I had 1 draw in kickboxing since the champ could not make weight the fight was changed to a exhibition match rather than for the record. When I watch the fight I can see he would have won on points. I lost 2 rage in the cage on decisions, I won the other three, 2 knockouts and 1 submission, and I lost the shoot fighting match, I was choked out.