Question

why does knife has sharp blade

Answer 1

The cutting edges of tools like blades, knives etc., areprovided with sharp edges to cut the things easily as the sharpedges has small area on which the force is applied, hence more pressure is applied

Answer 2

Since, The edge of knief is too thin due to which it's surface area is low.. And as we know that decreasing surface area results in increasing pressure,( as Pressure is inversally proportion to surface area) due to which knief is able to cut substances easily due to it's sharpness, cause:- Low surface area.