Question

The cutting edges of tools like knives, blades etc are provided with sharp edges. Explain why?

Answer 1

Hint: Materials can be cut easily if the pressure applied on them is high. The pressure applied on a body is inversely proportional to surface area. So, the less the surface area more is the pressure applied. But if the surface area is more, the pressure will be less.
Formula used:
 $P=\dfrac{F}{A}$

Complete answer:
From the mathematical expression,
$P=\dfrac{F}{A}$
We can say that for an equal amount of force applied, the pressure will be more by the body with a smaller surface area as compared to a body with larger surface area.
So, knives blades and other cutting appliances are designed with a sharper edge which provides for a smaller surface area and thus provides more pressure on the substance or material that is to be cut. This makes the entire process of cutting easier, efficient and less time consuming.
Thus, knives and blades have sharp edges because they provide less surface area relating to more Pressure.

Additional Information:
When the sharpness of knives and blades are worn out, they are made to recover their sharpness using various sharpening tools so that the ease of cutting remains intact. So it is very important for all cutting tools to be having sharp edges.

Note:
Care is taken so that cutting tools like knives and blades are not made too thin else it becomes very difficult to apply a large amount of force to them. In ensuring the edges are sharp, a balance is made so that these cutting tools are either too thin nor they have blunt edges.