moment of inertia and martial arts

[cookbeat01]

How does moment of inertia apply to all the martial arts kicks, punches and other moves?

[[Tycho?]]

Hahahahaha.

[swansont]

You want to perhaps narrow the scope of your question?

[Rebiu]

How does moment of inertia apply to all the martial arts kicks, punches and other moves?

That is an interesting question. Moment of inertia, I = mrr(Moment of inertia=Mass times radius squared, refers to the resistance to change in movement of a mass in a rotational context. Because human movement in achieved with joints all such movement is rotational.

 

In strikes that involve the fist, foot, elbow, or knee traveling in a predominately circular path to the target moment of inertia is relevant in several ways. The first is that the greater the length of the radius the longer it will take the blow to land. Sometimes this is desirable other times it can be mitigated by varying the radii throughout the strike by adopting more elliptical than circular pathways. This can be done in a two dimensional context with a hook punch by changing the extension of the elbow. It can be done in a three dimensional context, with the elbow, knee and kick by changing the elevation of the strike to vary the radii relative to the two-dimensional orbit.

 

Strikes that travel in a primarily straight path are accomplished by two or more circular path creating joints moving in opposite directions therefore combining to create a straight path. This may be the torso rotating in one direction while the shoulder rotates in the other.

[ydoaPs]

How does moment of inertia apply to all the martial arts kicks, punches and other moves?

it really depends on which move you are doing. moment of inertia applies in circular moves like crescent kicks, round kicks, elbow strikes, etc. which use circular paths when they hit their target.

 

some moves, like backside kicks, spin kicks, instant side kicks, punches, etc, may or may not have circular approaches, but the actual attack is linear. in those cases, momentum is what is used.

[hybrid04]

You also have to consider technique. Very infrequently is the leg extended the whole way when spinning. Usually you spin and then extend at the end. Then you have cm to consider for the person. Generally a useless and impractical thing to consider.

[swansont]

it really depends on which move you are doing. moment of inertia applies in circular moves like crescent kicks' date=' round kicks, elbow strikes, etc. which use circular paths when they hit their target.

 

some moves, like backside kicks, spin kicks, instant side kicks, punches, etc, may or may not have circular approaches, but the actual attack is linear. in those cases, momentum is what is used.[/quote']

 

If the strike does not go through your own center-of-mass, a torque will result on you, and if the strike does not go through your target's COM, there will be a torque there. So, there's a lot to consider here.