Question

Why does a sharp knife enable us to cut through things more easily?
A. The pressure exerted is lesser when the same force is used
B. The pressure exerted is greater when the same force is used
C. The sharp edge can pass through the material slowly
D. The sharp edge is not felt when cutting through the material

Answer 1

Hint: In order to solve this problem, we should know the concept of pressure. Pressure is defined as the force exerted on an object through a small area.

Complete step by step answer:
A very thin edge surface consists in a sharp knife to its blade. Its dimension is made such that a Sharp knife is used to cut the objects very easily because to its Sharpe thin edge, within a small area we apply the force by our hands and the large pressure produced by the object. Because of this large pressure cuts the object in better.
The knife exerts a greater pressure on the surface of the object due to the contact of a smaller area of cross section.
$pressure = \dfrac{{force}}{{area}}$
Hence the correct option is B.

Additional information: The pressure exerted on a surface by an object increases as the weight of the object increases or the surface area of contact decreases. If the weight of the object decreases then the pressure exerted on the object also decreases as the surface area of the cross section which is in contact increases.

Note: A blunt knife has a thicker edge. A blunt knife cannot cut an object easily because due to its large thickness at the edge of an object, the object produces lesser pressure because of the force applied by our hand on a larger area of the object. Hence the lesser pressure from the blunt knife cannot cut the object easily.