Question

Why are cutting instruments sharpened?

Answer 1

Hint: The application of cutting instruments such as knives, blades and many more are based upon the principle of pressure application. As we know that the pressure is defined as the force applied per unit of area. It can also be written as the formula in following way,
${\rm{Pressure = }}\dfrac{{{\text{Force applied}}}}{{{\rm{Area}}}}$
If the force applied is denoted by $F{\text{ in Newtons}}$ and the area is denoted by $A{\text{ in }}{{\rm{m}}^2}$ then the pressure is given by-
Pressure $\left( P \right) = \dfrac{F}{A}{\rm{ }}{{\rm{N}} {\left/
{\vphantom {{\rm{N}} {{{\rm{m}}^{\rm{2}}}}}} \right.
} {{{\rm{m}}^{\rm{2}}}}}$

Complete step by step answer:
The edge of the cutting instrument used for cutting other materials, also known as the “cutting edge” always possesses a very sharpened edge. This sharpened edge makes the cutting process easy and effortless.

By sharpening the edge of the cutting instrument, the area of the instrument decreases, the effect of this decrease in the area of the cutting edge can be understood by using the pressure formula, so from the formula of the pressure,
${\rm{Pressure = }}\dfrac{{{\text{Force applied}}}}{{{\rm{Area}}}}$
Now from this relation, if the area of the cutting tool decreases, the value of the pressure increases, which means that at the same value of applied force, we are getting more pressure. Due to this increase in the pressure value, the cutting process gets easier.
Therefore, we can say that the cutting instruments are sharpened to increase the value of the pressure and make the cutting process easy.

Note: It should be noted that by decreasing the area of the cutting instrument, we are increasing the value of pressure, but the life of the cutting instrument is decreased due to this. Because decreasing the area increases the internal stress developed in the cutting instrument and this stress reduces the life of the instrument.