question_answer

  A man squeezes a pin between his thumb and finger, as shown in figure. The finger exerts a force of 84 N on the pinhead. The pinhead has an area of . Explain why the pin causes more pain in the man's thumb than in his finger.  

Answer:

                  Pressure is the force per unit area. When a force acts over a large area of the object, it produces a small pressure. But if the same force acts over a small area of the object, it produces a large pressure. In this case surface area of pin tip is less than the surface area of pinhead. So pressure is more in man's thumb.