I'm trying to find out the equation you use for finding the force of a punch or kick in relation to the martial arts. Thanks

I have answered this question many times.

basic physics

e=mc^2 change of mass to energy or back
e=(mv^2)/(2) kinetic energy (note also equals e=ma). e=(0.5)mv^2 refers to only converting potential (positional) energy to kinetic energy (how much energy does you fist have when it moves). Perhaps with a change of constant value in front (usually given as 1/2).

moment arm = weight times length from focal point ==measured in pound feet.
torque = energy used in a circular path or half mass times rotational velcity^2 == measured in foot pounds.

the velocity squares the energy of impact. The mass only multiplies.

you hit with twice mass you two times harder.
you hit with twice velocity you hit four times harder.
you hit with twice mass and velocity you hit eight times harder.
you hit with three times the speed and hit nine times harder.

velocity is much more important than just mass. And that is before considering if you move that fast you can hit them before they can hit you, even if they start to swing first!

and the smaller the surface area the more pounds per square inch for the same amount of applied force so a smaller amount of contact area with target hits better than a wide contact area, if you want to increase pounds per square inch.

p=mv. Momentum equals mass times velocity

also consider the movement of the hips, shoulders, legs, length of stepping forward, or the arc distance of angular velocity when pivoting, in your calcutations of distance moved.

rate multiplied times time equals distance. d=r/t.
5 miles = 5 miles per hour multiplied by one hour. 5 miles = 5 mi/1 hr * 1 hr.
energy = distance times time. e=dt.

if you are off the ground (like in kendo), and let whatever you make contact with become the point of you trying to stay off the ground (put your body weight into it) then you have put your entire body weight into the blow (strike). And your entire body weight is more force (f=ma==w=mg.weight is mass times gravity, and a type of force, i.e. has the same dimensionality or units) than most people bring to a strike.

I hope this helps. eawoodall