the wall. however, pushing with the same force while using a thumbtack can punch through the wall as the force is concentrated into the point of the thumbtack. concentrating the same force over a smaller area results in an increase in pressure. the same principle is behind the operation of a knife. if you tried to cut with the flat edge of a knife it will not be very effective. turning the knife on its sharp edge makes it more effective at cutting as the applied force is concentrated over a smaller area. likewise, a large force can exert a small pressure if that force is distributed over a large 