Question

why do nails have pointed tips?
A. It enhances their look.
B. It reduces the force required to fix it in the wall.
C. It increases strength.
D. It makes it easy to handle.

Answer 1

Hint: The tip of a nail is sharp and pointed so that the area under the pointed end of a sharp nail is so small. As a result, the pressure exerted by a sharp nail on the wall is greater, and it may pierce the wall with less effort.

Complete answer:
Pressure is the force acting on a unit area, also pressure is inversely proportional to the area. If the force is applied to the larger area its pressure is less and if the same force acts on a very small area then its pressure is greater. Force, area and pressure is related by the equation,
$\text{Pressure} = \dfrac{\text{Force}}{\text{Area}}$

So when the tip of the nail is pointed the area of the surface with contact with the wall decreases and to get the enough pressure to pierce the wall the person will have to apply less force, decreasing the effort to be made.

Therefore, the correct option is B.

Note: The SI unit for pressure is the Pascal (Pa), equal to one Newton per square meter ($N/m^2$, or $kg·m^{−1}·s^{−2}$). Another example of this same situation is, cutting a vegetable with a sharp knife is much easier than using a blunt knife, because a sharp knife is pointy at the end so it will have a reduced area of contact with the vegetable.