Punch, kicks, collisions in athletic contests

[corochena]

Why when a boxer, mma artist, football player, or any other athlete makes a collision such as a punch, kick or tackle we measure that using Force units (pounds or kilograms)?

Would not make more sense use Energy units or Impulse units?

I was just watching espn and they say a football player tackles with 1 ton force, what do they mean?

 

[yungman]

Energy don't necessary cause damage, pain. You can spend the same amount of energy over long period of time and do no damage...eg. pushing you with my hand continuously and move you back two step or a punch that transfer the same amount of energy in 1/100 of a second. The energy is the same, but the impact is a different world. In case one, you just laugh, and the second case, you might drop!

It is the time it dicipate the same energy that make the major difference.

 

[corochena]

yungman, you are right, but implicitly there is a time in the punch, kick or tackle, just we don't know exactly its value, but you can imagine or estimate it

I will know that if I get punched by a 4 kg mass at 10 m/s speed I will receive 20 J energy in about 0.1 second, so even if I don't know exactly what is the time involved I know we are talking about split seconds

... but Force? maybe even pressure it is better to give an idea for a collision damage

 

[yungman]

I am an electrical person, not mechanical oriented. I just join in because I am into Martial Arts. I think I should quit while I am ahead and let others that are expert in this to talk to you.

Happy New Year.

 

[russ_watters]

Energy don't necessary cause damage, pain. You can spend the same amount of energy over long period of time and do no damage...eg. pushing you with my hand continuously and move you back two step or a punch that transfer the same amount of energy in 1/100 of a second. The energy is the same, but the impact is a different world. In case one, you just laugh, and the second case, you might drop!

It is the time it dicipate the same energy that make the major difference. [emphasis added]

...which is why the OP also said impulse.

 

[russ_watters]

Why when a boxer, mma artist, football player, or any other athlete makes a collision such as a punch, kick or tackle we measure that using Force units (pounds or kilograms)?

Would not make more sense use Energy units or Impulse units?

I was just watching espn and they say a football player tackles with 1 ton force, what do they mean?

Yes, when people come here, they often ask about force of an impact, but we generally try to steer them away. Energy is actually a pretty good measure as long as it is stipulated that the energy exchange is in an impact (a very short interaction). Bone breakage can be modeled very similar to how a metal bar breaks from an impact, which is measured with a Charpy tester: http://www.google.com/search?source...z=1T4ADBF_enUS311US311&q=charpy+impact+tester

Using a pendulum striking an object, you can very easily measure the energy required to break that object.

For a car crash, energy is also a good measure: the kinetic energy of the car goes into the impact.

 

[corochena]

So I guess the sport tv channels use Force instead of Energy or Impulse just because Force (Pounds, ton, kg) is more common term, less people would understand if they used Joules or Kg.m/s

 

[phever]

they mean the amount of impulsive force delivered and in normal units so that people can understand .