Question

explain why the edge of a knife should be sharp

Answer 1

We know that greater the area of contact lesser will be the force created.And lesser the area greater would be the force.So the knife should have a smaller edge which can be attained by sharpening it,in order to cut or pass through any object with fewer force provided.

Answer 2

the edge of knife should be sharp because due to smaller area the pressure is small and the object can be cut easily