How do you find out how much psi your hitting with

[jarrettmeyer]

iolair is correct. Looks like someone studied his physics.

 

A deformable object will absorb the result and lower the PSI value.

 

PSI = POUNDS per SQUARE INCH

 

Pounds = (mass of striking object in slugs) x (acceleration in ft per second per second)

 

You can get a theoretical maximum, assuming linear acceleration. Take your total mass (M= weight in pounds/ 32.2) measure the distance your arm travels (L= in feet) and time how quickly your fist can travelled distance (T= in seconds). Also calculate the surface area of your striking zone. (S= in square inches).

 

If you *could* get 100% of your mass into a punch, then your maximum possible PSI is (M*L)/(S*T*T). This means that you are able to get, literally, your whole body into a punch: hand, arm, shoulder, hips, legs, toes, spleen, hair follicles, metatarsels, etc. But that's why they call it a theoretical maximum. It's unattainable. Shy of a flying kick, some of your mass is maintaining a frictional coefficient to keep your stance planted on the ground. Some of your mass is counterbalancing your punch. Unless, of course, your punch is so wild that you unable to remain standing after you swing it, and you slide across the dojo floor as if it were made of ice.

 

At least you can take a moment to see what this really all means. It has good application to combat. (1) Mass. The more of your body that goes into a swing, the more you can do. (2) Length. The further a strike travels, the more damage it does. (3) Square Inches. Surface area is in the denominator, so a smaller strike zone will create greater penetration. So, hit with the first two knuckles, instead of all four. (4) Time. Time is in the denominator, so a smaller number drives the amount of force higher. In fact of all the numbers, this may be the most significant, since it is squared. Caeteris paribus, a small increase in quickness returns a squared increase in force generated.

 

Physics is wonderful!

[JerryLove]

You can get a theoretical maximum, assuming linear acceleration. Take your total mass (M= weight in pounds/ 32.2) measure the distance your arm travels (L= in feet) and time how quickly your fist can travelled distance (T= in seconds). Also calculate the surface area of your striking zone. (S= in square inches).

Even if your whole body was involved, it assumes liniar speed (speed ramps up and down), and ignore pushing from the ground.

[TeaL]

for PSI, you just need speed, and wieght. and *divided by area*.

 

you dont actuily have to hit anything. it can be done much easyer in numbers.

For PSI ... pounds per square inch ... you need to know the number of pounds.

 

Pounds is a measure of FORCE. Speed itself does not tell us about force. Newton's Second Law of Motion tells us Force is equal to mass times acceleration. Acceleration is a _Change_ in speed. Something can quite happily continue at a steady speed with no acceleration, and therefore no force, occurring.

 

what i was saying is a simple example, i wasnt calculating obeject deseitys, or gravity or any resistance for that matter, but i think your a bit confused, by your definition, an object that accelorated to 100 MPH will hit harder then an ojbect traveling 100 MPH..ALSO psi = pressure per square inch...

 

I was also trying to use a real example, for his sake, he asked how hard he would hit, i figured he wanted to know like how much force was being applyed, to a cerint area to cause damage... thats why i added in SA

[jarrettmeyer]

For our discussion a 100 mph impact will be the same whether is went from 0 to 100 in a fraction of a second, or it has been travelling at 100 mph for the past year. The impact creates an instantaneous deceleration on the striking surface. That's just acceleration with a negative number! That deceleration is recognized a transfer of force from the striking object to the object being struck. That transfer in force divided by the surface area is the pressure generated. This is also why you want to use a rigid target. Anything that absorbs the force will reduce the recorded pressure. If you hit something TOO rigid, then your metatarsels, tarsels, radius, ulna, humerus, scapula, and associated cartilage must absorb the deceleration.

 

(Note: now we are getting more specific, and this complete destroys my linear acceleration from my previous model.)

 

In this particular example, we were using PSI = Pounds per Square Inch as a measurement of pressure. You could also use MPa = Newton per Square Millimeter or any other number of units to represent pressure.

[longarm25]

I May be off base but when i hit someone i psi is the last thing im worried about. sure i want to hit them as hard as possible but im not thinking I need to get him with 700-1000 psi so why focus on such a trival endevour?

[TeaL]

I May be off base but when i hit someone i psi is the last thing im worried about. sure i want to hit them as hard as possible but im not thinking I need to get him with 700-1000 psi so why focus on such a trival endevour?

 

Its not about how hard hes hitting, hes just insecure about his size.. which i am too, and he wants to know if he'll actuily do damage to him..

 

i have the same problem, somtimes i look at a guy, and think even if i ran and dragon kicked him in the torso, he wouldnt even notice.

[TeaL]

I May be off base but when i hit someone i psi is the last thing im worried about. sure i want to hit them as hard as possible but im not thinking I need to get him with 700-1000 psi so why focus on such a trival endevour?

 

Its not about how hard hes hitting, hes just insecure about his size.. which i am too, and he wants to know if he'll actuily do damage to him..

 

i have the same problem, somtimes i look at a guy, and think even if i ran and dragon kicked him in the torso, he wouldnt even notice.

[jarrettmeyer]

You can rest assured that the human body is actually incredibly frail.

 

12 pounds of force will snap that collarbone in two.

 

30 pounds of downward pressure will rip off someone's ear.

 

25 pounds of the knee bent laterally will tear the ACL.

 

16 pounds will break any of the fingers backwards towards the wrist.

 

5 pounds to the neck can break the windpipe.

 

Your half-speed practice movements, delivered with correct technique, is enough to kill a person. If the same blow to the collar bone goes just a little south, all you do is tick the guy off and maybe bruise his ribs.

[iolair]

iolair is correct. Looks like someone studied his physics.

Actually, I teach it

[iolair]

It would be important to have a non-deforming object, because otherwise energy is going into deforming the object and not into making it swing up.

 

A non-deforming object hey? sounds hard, like steel? i think perhaps if you punched a non-deformable object as hard as you could your fist would deform badly and you would lose alot of energy

If you hit a FIXED non-deforming object, maybe... but this one is gonna SWING, remember... And it doesn't need to be 100% non-deforming, it's just the more it squishes, the more of your punch energy is going to squish it instead of making it swing.