Dear forum, I have the following phisics problem. I want to be able to measure the impact of a punch in a regular punching bag. I'm able to measure the acceleration in all the three axis. Besides that I know the punching bag dimensions and weight. The colision between the fist and the bag is not ellastic. Substacial energy is absorbed by the bag. Below I present some pictures of the setup. I'm looking for the physical differential equations that relates the acceleration and the impact force on the bag. Any help will be appreciated. Regards to all.