Question

If someone presses a pointed needle against your skin, you are hurt. But if someone presses a rod against your skin with the same force, you easily tolerate. Explain.

Answer 1

It is because of the pressure in the case of the needle is more than the pressure in the case of the rod. Suppose the same force F is applied in both cases. If the area of needlepoint =a and the area of the rod =A so that A>a. The pressure of needlepoint F/a >F/A. So the needlepoint hurts.