I always wondered why is hurt so much when you punched something. Besides the obviously answer of: "It's a hard surface against your little hand" I never truly had an answer until we learned about Newton's Laws. Newton's Third Law helped to answer my question. According to Newton, when you put any force on any object, the amount of force you exert will be exerted back on you. Punching a wall, punching a person, or anything like that results in pain because all the force you exerted comes right back onto you.