Question

Why is it easy to cut vegetables with a sharp knife?

Answer 1

Hint: A sharp knife is characterized by a very narrow edge as compared to a usual iron rod or a blunt knife. We apply force on the knife to cut the vegetables. There is a relation between the force applied, the area of contact, and the impact on the vegetable.

Complete step-by-step solution
We are all well aware of the forces in nature. Every action requires a force to be applied. Whether it is to start motion, continue a motion, or to halt a motion we have to work in a prescribed manner for a favorable outcome. The force applied can be utilized by the body receiving the force according to the quantity of force applied, its orientation with the force, and the area of contact.
The pressure is this factor, which determines the utilization of force with the area. The pressure is defined as the force per unit area.
\[\begin{align}
  & \text{Pressure},\text{ }P=\dfrac{Force,F}{Area,A} \\
 & \text{i}\text{.e}\text{., }P=\dfrac{F}{A} \\
\end{align}\]
From the formula of the pressure, we can understand that the area involved is inversely proportional to the pressure experienced by the body. In other words, the higher the area of contact, the lesser will be the pressure experienced by the object.
This principle is the theory behind using sharp knives instead of blunt ones. A sharp knife has a relatively lesser area of contact with the vegetable, as a result, the force can effectively be concentrated on the area without getting wasted.
Therefore, we always use a sharp knife in a knife for efficiency.

Additional Information: The daily paper and pencil accessories like a pin, scissors, and other things use this same principle.

Note: Pascal's theory on force distribution is an inverse application of this relation between the area of contact and the pressure. A heavy load is easily lifted by applying a relatively very small force over a small area. This pressure is taken to a larger area and converted to force enough to lift heavy objects.