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.

Question

Philoid · Accepted Answer

The pressure (P) on any surface depends on the force(F) and area(A) as given by:

Now, lesser the area of contact of the object, higher will be the pressure. In case of a needle, the area of contact is just a point as compared to a rod. Hence the same amount force will produce a larger pressure in case of a needle, because of which we can get hurt.