1. The problem statement, all variables and given/known data I am working on a physics project about karate, and I want to know how fast I would have to punch to break a practice concrete slab. I know that the slab requires 1900 newtons to break. I also know that my arm has an approximate mass of 8.4 kg. I also know that my arm is about 80 cm long, which is basically the distance my punch will travel. 2. Relevant equations F = ma 3. The attempt at a solution If I simply use F = ma, it tells me that I must punch at 226 m/s to break the concrete...that doesn't seem right to be. I know I'm probably oversimplifying the problem...could someone point me in the right direction?