When hitting a wall, the pain experienced is due to contact forces, primarily the normal force, which is an electromagnetic force. This force arises from the electromagnetic repulsion between the electron shells of atoms in the hand and those in the wall. As the hand makes contact, nerve endings send electric pulses to the brain, signaling pain. The stopping force is not just mechanical but fundamentally rooted in electromagnetic interactions. Understanding these forces highlights the complex nature of physical interactions at the atomic level.